Methods of fabricating nanostructures and nanowires and devices fabricated therefrom

• US 20020175408A1
• Filed: 03/29/2002
• Published: 11/28/2002
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Yang, Peidong, Huang, Michael, Mao, Samuel S., Fan, Rong, Shakouri, Ali, Wu, Yiying, Majumdar, Arun, Sands, Timothy D., Russo, Richard E., Kind, Hannes, Weber, Eicke R., Feick, Henning, Yan, Haoquan
• Granted Patent: US 6,882,051 B2
• Time in Patent Office: Days
• US Class Current: 257/734
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/107 Subwavelength-diameter waveguides, e.g. nanowires
• CPC Class Codes: H01L 21/0237 Materials
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• CPC Class Codes: H01L 21/0245 Silicon, silicon germanium, germanium
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• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02554 Oxides
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• CPC Class Codes: H01L 2224/45599 Material
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• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 29/0665 the shape of the body defining a nanostructure nanotechnology per se B82B
• CPC Class Codes: H01L 29/0673 oriented parallel to a substrate
• CPC Class Codes: H01L 29/0676 oriented perpendicular or at an angle to a substrate
• CPC Class Codes: H01L 29/068 comprising a junction
• CPC Class Codes: H01L 29/12 : characterised by the materials of which they are formed
• CPC Class Codes: H01L 29/125 : Quantum wire structures
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
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• CPC Class Codes: H01S 5/3412 : quantum box or quantum dash
• CPC Class Codes: H10N 10/00 : Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects integrated devices or assemblies of multiple devices H10N19/00
• CPC Class Codes: H10N 30/2042 : Cantilevers, i.e. having one fixed end
• CPC Class Codes: H10N 30/85 : Piezoelectric or electrostrictive active materials
• CPC Class Codes: H10N 30/852 : Composite materials, e.g. having 1-3 or 2-2 type connectivity
• CPC Class Codes: Y10S 977/762 : Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/763 : formed along or from crystallographic terraces or ridges
• CPC Class Codes: Y10S 977/764 : with specified packing density
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• CPC Class Codes: Y10T 428/2958 : Metal or metal compound in coating
• CPC Class Codes: Y10T 428/2973 : Particular cross section
• CPC Class Codes: Y10T 428/298 : Physical dimension

Abstract

One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as “nanowires”, include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).

Claims

1. A nanowire, comprising:

a first segment of a first material; and

a second segment of a second material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm; and

wherein said nanowire is selected from a population of nanowires having a substantially monodisperse distribution of diameters.

47. A nanowire as recited in claim 1, 2, 3 or 4, wherein at least one of said materials comprises a substantially crystalline material.

48. A nanowire as recited in claim 1, 2, 3, 4, 6, 12, 16, 21, 26, 30, 35, 40 or 44, wherein said first and second materials are compositionally different materials.

49. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 35, 40 or 44, wherein at least one of said segments comprises a substantially monocrystalline material.

50. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12 or 16, wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 100 nm.

51. A nanowire as recited in claim 50, wherein said transition occurs over a region that is substantially defect free.

52. A nanowire as recited in claim 50, wherein said transition occurs over a region that is substantially crystalline.

53. A nanowire as recited in claim 50, wherein said transition occurs over a region that is substantially monocrystalline.

54. A nanowire as recited in claim 50, wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of said first segment at the center of said first segment.

55. A nanowire as recited in claim 1, 2, 3, 4, 5, 6, 10, 12 or 16, wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm.

56. A nanowire as recited in claim 55, wherein said transition occurs over a region that is substantially defect free.

57. A nanowire as recited in claim 55, wherein said transition occurs over a region that is substantially crystalline.

58. A nanowire as recited in claim 55, wherein said transition occurs over a region that is substantially monocrystalline.

59. A nanowire as recited in claim 55, wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of said first segment at the center of said first segment.

60. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 19, 21, 33 or 35, wherein at least one of said segments comprises a semiconductor material.

61. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 19, 21, 26, 33, 35 or 40, wherein at least one of said segments comprises a doped semiconductor material.

62. A nanowire as recited in claim 1, 2, 3, 4, 6, 20, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein at least one of said segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

63. A nanowire as recited in claim 1, 2, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said at least one of said segments having a diameter of less than approximately 200 nm has a diameter ranging from approximately 5 nm to approximately 50 nm.

64. A nanowire as recited in claim 1, 2, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 50% over the length of said segment.

65. A nanowire as recited in claim 1, 2, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

66. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said second segment is longitudinally adjacent said first segment.

67. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said second segment is coaxially adjacent said first segment.

68. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said first segment comprises a substantially monocrystalline material.

69. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said second segment comprises a substantially monocrystalline material.

70. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said first and second segments form a p-n junction.

71. A nanowire as recited in claim 70, wherein said nanowire comprises a semiconductor device.

72. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said first and second segments form a p-i junction.

73. A nanowire as recited in claim 72, wherein said nanowire comprises a semiconductor device.

74. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said first and second segments form a i-n junction.

75. A nanowire as recited in claim 74, wherein said nanowire comprises a semiconductor device.

76. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, further comprising an electrode electrically coupled to at least one of said segments.

77. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein at least one of said segments comprises a material selected from the group of elements consisting essentially of group II, group III, group IV, group V, group VI elements, and tertiaries and quaternaries thereof.

78. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein at least one of said segments is embedded in a polymer matrix.

79. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein at least a portion of at least one of said segments is covered by a sheath.

80. A nanowire as recited in claim 79, wherein said sheath comprises an amorphous material.

81. A nanowire as recited in claim 79, wherein said sheath comprises a substantially crystalline material.

82. A nanowire as recited in claim 81, wherein said substantially crystalline material is substantially monocrystalline.

83. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44:

wherein said nanowire is a functional component of a device selected from the group of devices consisting essentially of phonon bandgap devices, quantum dot devices, thermoelectric devices, photonic devices, nanoelectromechanical actuators, nanoelectromechanical sensors), field-effect transistors, infrared detectors, resonant tunneling diodes, single electron transistors, infrared detectors, magnetic sensors, light emitting devices, optical modulators, optical detectors, optical waveguides, optical couplers, optical switches, and lasers.

84. A nanowire as recited in claim 1, 2, 3, 4, 6,10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, wherein said nanowire is an element of an array of nanowires.

85. A nanowire as recited in claim 84, wherein said array comprises an oriented array.

86. A nanowire as recited in claim 84, wherein each of said nanowires in said array is oriented at an angle substantially normal to a substrate.

87. A nanowire as recited in claim 84, wherein each of said nanowires in said array is oriented at an angle that is not normal to a substrate.

88. A nanowire as recited in claim 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44, electrically coupled to a second nanowire wherein a junction is formed.

90. A nanowire as recited in claim 88, wherein said nanowire is inductively coupled to said second nanowire.

91. A nanowire as recited in claim 88, wherein said nanowire forms a tunneling junction with said second nanowire.

92. A nanowire as recited in claim 88, wherein said junction has a substantially linear voltage-current relationship.

93. A nanowire as recited in claim 88, wherein said junction has a substantially non-linear voltage-current relationship.

94. A nanowire as recited in claim 88, wherein said junction has a substantially step function voltage-current relationship.

95. A nanowire collection, comprising:

a plurality of a nanowires as recited in any of claims 1, 2, 3, 4, 6, 10, 12, 16, 19, 21, 26, 30, 33, 35, 40 or 44.

96. A nanowire collection as recited in claim 95, wherein said collection comprises greater than approximately 100 nanowires.

97. A nanowire collection as recited in claim 95, wherein said collection comprises greater than approximately 1000 nanowires.

98. A nanowire collection as recited in claim 95, wherein greater than 80% of the members of said collection comprise substantially the same heterostructure.

99. A nanowire collection as recited in claim 95, wherein substantially all of the members of said collection exhibit substantially the same heterostructure.

100. A nanowire collection as recited in claim 95, wherein the members of said collection comprise at least two different species of nanowire.

101. A nanowire collection as recited in claim 95, wherein the members of said collection comprise at least ten different species of nanowire.

102. A nanowire collection as recited in claim 95, wherein said collection is suspended in a fluid.

103. A nanowire collection as recited in claim 95, wherein said collection is suspended by a material selected from the group consisting essentially of a liquid, a glass, a gel, and a gas.

104. A nanowire collection as recited in claim 95, wherein said collection is suspended or embedded in a matrix.

105. A nanowire collection as recited in claim 95, wherein one or more members of said collection is electrically coupled to one or more other members of said collection.

106. A nanowire collection as recited in claim 105, wherein one or more members of said collection is in ohmic contact with one or more other members of said collection.

107. A nanowire collection as recited in claim 105, wherein one or more members of said collection is inductively coupled with one or more other members of said collection.

108. A nanowire collection as recited in claim 105, wherein one or more members of said collection forms a tunneling junction with one or more other members of said collection.

109. A nanowire collection as recited in claim 105, wherein said electric coupling has a substantially non-linear voltage-current relationship.

110. A nanowire collection as recited in claim 105, wherein said electric coupling has a substantially linear voltage-current relationship.

111. A nanowire collection as recited in claim 105, wherein said electric coupling has a substantially step function voltage-current relationship.

112. A nanowire collection as recited in claim 95, wherein said collection has a substantially monodisperse distribution of nanowire diameters.

113. A collection of nanowires as recited in claim 95, wherein said collection has a substantially monodisperse distribution of nanowire lengths.

115. A nanowire as recited in claim 114, wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

116. A nanowire as recited in claim 114, wherein said nanowire transitions from at least one of said segments to an adjacent segment over a distance ranging from approximately one atomic layer to approximately 20 nm.

117. A nanowire as recited in claim 116, wherein said transition begins at a point moving from said at least one of said segments toward said adjacent segment where the composition of said at least one of said segments has decreased to approximately 99% of the composition of that segment at its center.

118. A nanowire as recited in claim 114, wherein at least two of said segments are longitudinally adjacent.

120. A nanowire as recited in claim 114, wherein at least two of said segments are coaxially adjacent.

121. A nanowire as recited in claim 114, wherein at least one of said materials comprises a substantially crystalline material.

122. A nanowire as recited in claim 114, wherein said substantially crystalline material is substantially monocrystalline.

123. A nanowire as recited in claim 114, wherein at least one of said segments comprises a semiconductor material.

124. A nanowire as recited in claim 114, wherein at least one of said segments comprises a doped semiconductor material.

125. A nanowire as recited in claim 114, wherein at least one of said segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

126. A nanowire as recited in claim 114, wherein said at least one of said segments having a diameter of less than approximately 200 nm has a diameter ranging from approximately 5 nm to approximately 50 nm.

127. A nanowire as recited in claim 114, wherein at least two of said segments form a p-n junction.

128. A nanowire as recited in claim 114, wherein at least two of said segments form a p-i junction.

129. A nanowire as recited in claim 114, wherein at least two of said segments form a i-n junction.

130. A nanowire as recited in claim 114, wherein said segments form p-n-p junctions.

131. A nanowire as recited in claim 114, wherein said segments a n-p-n junctions.

132. A nanowire as recited in claim 114, wherein said segments form p-i-n junctions.

133. A nanowire as recited in claim 114, wherein said segments form p-i-p junctions.

134. A nanowire as recited in claim 127, 128, 129, 130, 131, 132 or 133, wherein said nanowire comprises a semiconductor device.

135. A nanowire as recited in claim 114, further comprising an electrode electrically coupled to at least one of said segments.

136. A nanowire as recited in claim 114, wherein at least one of said segments comprises a material selected from the group of elements consisting essentially of group II, group III, group IV, group V, and group VI elements, and tertiaries and quaternaries thereof.

137. A nanowire as recited in claim 114, wherein at least one of said segments is embedded in a polymer matrix.

138. A nanowire as recited in claim 114, wherein at least a portion of at least one of said segments is covered by a sheath.

139. A nanowire as recited in claim 138, wherein said sheath comprises an amorphous material.

140. A nanowire as recited in claim 138, wherein said sheath comprises a substantially crystalline material.

141. A nanowire as recited in claim 140, wherein said substantially crystalline material is substantially monocrystalline.

143. A nanowire as recited in claim 114, wherein said nanowire is an element of an array of nanowires.

147. A method of claim 146, wherein said first and second gas reactants further comprise a carrier gas.

164. A method as recited in claim 163, wherein said substrate comprises an element selected from the group of elements consisting essentially of group III and group IV elements.

165. A method as recited in claim 163, wherein said metal comprises gold.

166. A method as recited in claim 165, wherein said gold comprises colloidal gold.

168. A method as recited in claim 163, wherein said furnace comprises a quartz furnace reaction tube.

169. A method as recited in claim 163, wherein said gas reactant comprises a mixture of mixture of H₂ and SiCl₄.

171. A method as recited in claim 170, further comprising:

pulsing said laser on and off;

wherein a Si/SiGe superlattice is formed in a block-by-block fashion.

172. A method as recited in claim 170, wherein said substrate comprises an element selected from the group of elements consisting essentially of group III and group IV elements.

173. A method as recited in claim 170, wherein said gold comprises colloidal gold.

174. A method as recited in claim 170, wherein said substrate comprises silicon.

175. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

176. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm.

177. A method as recited in claim 176, wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of th e composition of said first segment at the center of said first segment.

178. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein at least one of said segments comprises a substantially crystalline material.

179. A method as recited in claim 178, wherein said substantially crystalline material is substantially monocrystalline.

180. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein at least one of said segments comprises a semiconductor material.

181. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising doping at least one of said segments.

182. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein said at least one of said segments having a diameter of less than approximately 200 nm has a diameter ranging from approximately 5 nm to approximately 50 nm.

183. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein said second segment is longitudinally adjacent said first segment.

184. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein said second segment is coaxially adjacent said first segment.

185. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising doping said first and second segments to form a p-n junction.

186. A method as recited in claim 185, wherein said nanowire comprises a semiconductor device.

187. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising doping a said one of said segments to form a p-i junction.

188. A method as recited in claim 187, wherein said nanowire comprises a semiconductor device.

189. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising doping a said one of said segments to form a i-n junction.

190. A method as recited in claim 189, wherein said nanowire comprises a semiconductor device.

191. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising electrically coupling an electrode to at least one of said segments.

192. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein at least one of said segments comprises a material selected from the group of elements consisting essentially of group II, group III, group IV, group V, and group VI elements, and tertiaries and quaternaries thereof.

193. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising embedding at least one of said segments in a polymer matrix.

194. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, further comprising depositing a sheath over a portion of at least one of said segments.

195. A method as recited in claim 194, wherein said sheath comprises an amorphous material.

196. A method as recited in claim 194, wherein said sheath comprises a substantially crystalline material.

197. A method as recited in claim 196, wherein said substantially crystalline material is substantially monocrystalline.

198. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170:

wherein said nanowire is a functional component of a device selected from the group of devices consisting essentially of phonon bandgap devices, quantum dot devices, thermoelectric devices, photonic devices, nanoelectromechanical actuators, nanoelectromechanical sensors), field-effect transistors, infrared detectors, resonant tunneling diodes, single electron transistors, infrared detectors, magnetic sensors, light emitting devices, optical modulators, optical detectors, optical waveguides, optical couplers, optical switches, and lasers.

199. A method as recited in claim 144, 151, 155, 156, 160, 161, 163 or 170, wherein said nanowire is an element of an array of nanowires.

2. A nanowire, comprising:

a first segment of a first material; and

a second segment of a second material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm; and

wherein said nanowire is selected from a population of nanowires having a substantially monodisperse distribution of lengths.

3. A nanowire, comprising:

a first segment of a first material; and

a second segment of a second material joined to said first segment;

said nanowire displaying characteristics selected from the group consisting essentially of electronic properties, optical properties, physical properties, magnetic properties and chemical properties that are modified relative to the bulk characteristics of said first and second materials by quantum confinement effects.

4. A nanowire, comprising:

a first segment of a first material; and

a second segment of a second material joined to said first segment;

said nanowire having at least one electronic property that varies as a function of diameter of said nanowire.

5. A nanowire as recited in claim 4, wherein said at electronic property comprises band-gap energy.

6. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a substantially crystalline material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

7. A nanowire as recited in claim 6, wherein each of said first and said second segments comprises a doped semiconductor material.

8. A nanowire as recited in claim 7, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

9. A nanowire as recited in claim 6, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

10. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a compositionally different material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

11. A nanowire as recited in claim 10, wherein said second segment comprises a substantially crystalline material.

13. A nanowire as recited in claim 12, wherein each of said first and said second segments comprise a doped semiconductor material.

14. A nanowire as recited in claim 13, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

15. A nanowire as recited in claim 12, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

17. A nanowire as recited in claim 16, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

18. A nanowire as recited in claim 16, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

20. A nanowire as recited in claim 19, wherein said second segment comprises a substantially crystalline material.

12. A nanowire, comprising:

a first segment of semiconductor material; and

a second segment of semiconductor material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

16. A nanowire, comprising:

a first segment of doped semiconductor material; and

a second segment of doped semiconductor material joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

19. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a compositionally different material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

21. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a substantially crystalline material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

22. A nanowire as recited in claim 21, wherein each of said first and said second segments comprises a semiconductor material.

23. A nanowire as recited in claim 21, wherein each of said first and said second segments comprises a doped semiconductor material.

24. A nanowire as recited in claim 23, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

25. A nanowire as recited in claim 21, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

27. A nanowire as recited in claim 26, wherein each of said first and said second segments comprises a doped semiconductor material.

28. A nanowire as recited in claim 27, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

29. A nanowire as recited in claim 26, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

26. A nanowire, comprising:

a first segment of semiconductor material; and

a second segment of semiconductor material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

30. A nanowire, comprising:

a first segment of doped semiconductor material; and

a second segment of doped semiconductor material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

31. A nanowire as recited in claim 30, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

32. A nanowire as recited in claim 30, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

33. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a compositionally different material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm;

wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of said first segment at the center of said first segment; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

34. A nanowire as recited in claim 33, wherein said second segment comprises a substantially crystalline material.

36. A nanowire as recited in claim 35, wherein each of said first and said second segments comprises a semiconductor material.

37. A nanowire as recited in claim 35, wherein each of said first and said second segments comprises a doped semiconductor material.

38. A nanowire as recited in claim 37, wherein said doped semiconductor material is selected from the group consisting essentially of a group II-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

39. A nanowire as recited in claim 35, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

35. A nanowire, comprising:

a first segment of a substantially crystalline material; and

a second segment of a substantially crystalline material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm;

wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of said first segment at the center of said first segment;

wherein at least one of said segments has a diameter of less than approximately 200 nm; and

wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

40. A nanowire, comprising:

a first segment of semiconductor material; and

a second segment of semiconductor material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm;

wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of said first segment at the center of said first segment;

wherein at least one of said segments has a diameter of less than approximately 200 nm; and

wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

41. A nanowire as recited in claim 40, wherein each of said first and said second segments comprises a doped semiconductor material.

42. A nanowire as recited in claim 41, wherein said doped semiconductor material is selected from the group consisting essentially of a group III-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

43. A nanowire as recited in claim 40, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

44. A nanowire, comprising:

a first segment of doped semiconductor material; and

a second segment of doped semiconductor material joined to said first segment;

wherein said nanowire transitions from said first segment to said second segment over a distance ranging from approximately one atomic layer to approximately 20 nm;

wherein transition from said first segment to said second segment begins at a point toward said second segment where the composition of said first segment has decreased to approximately 99% of the composition of the first segment at the center of said first segment;

wherein at least one of said segments has a diameter of less than approximately 200 nm; and

wherein the diameter of said at least one of said segments having a diameter of less than approximately 200 nm does not vary by more than approximately 10% over the length of said segment.

45. A nanowire as recited in claim 44, wherein said doped semiconductor material is selected from the group consisting essentially of a group II-V semiconductor, a group II-VI semiconductor, a group II-IV semiconductor, and tertiaries and quaternaries thereof.

46. A nanowire as recited in claim 44, wherein each of said first and second segments exhibits the electrical characteristics of a homogeneously doped semiconductor.

89. A nanowire as recited in 88, wherein said nanowire is in ohmic contact with said second nanowire.

114. A nanowire, comprising:

a first segment of a first material;

a second segment of a second material joined to said first segment; and

a third segment of a third material joined to at least one of said first and second segments;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm;

wherein at least two of said materials comprise compositionally different materials; and

wherein at least two of said segments are adjacent.

119. A nanowire as recited in claim 114:

wherein said second segment is longitudinally adjacent said first segment; and

wherein said third segment is longitudinally adjacent said second segment.

142. A nanowire as recited in claim 114:

wherein said nanowire is a functional component of a device selected from the group of devices consisting essentially of phonon band gap devices, quantum dot devices, thermoelectric devices, photonic devices, nanoelectromechanical actuators, nanoelectromechanical sensors), field-effect transistors, infrared detectors, resonant tunneling diodes, single electron transistors, infrared detectors, magnetic sensors, light emitting devices, optical modulators, optical detectors, optical waveguides, optical couplers, optical switches, and lasers.

144. A method of fabricating a nanowire, comprising:

dissolving a first gas reactant in a catalytic liquid followed by growth of a first segment; and

dissolving a second gas reactant in said catalytic liquid followed by growth of a second compositionally different segment joined to said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

145. A method as recited in claim 144:

wherein a compositionally dissimilar liquid alloy is formed from each said gas reactant and said catalytic liquid; and

wherein each said segment forms upon saturation of said liquid alloy with a species of said corresponding gas reactant.

146. A method as recited in claim 144:

wherein said first and second gas reactants comprise vapors generated by laser ablation of a first and second growth species respectively.

148. A method as recited in claim 144:

wherein said second gas reactant comprises a vapor generated by laser ablation of a growth species; and

wherein said second segment comprises a combination of said species in said first and second gas reactants.

149. A method as recited in 144, wherein said catalytic liquid is formed from a preformed metal colloid.

150. A method as recited in 149, wherein said metal colloid is part of a population of metal colloids with a substantially monodisperse distribution of diameters.

151. A method of fabricating a nanowire, comprising:

dissolving a gas reactant in a catalytic liquid followed by growth of a first segment; and

coating said first segment with a compositionally different second material and forming a second segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

152. A method as recited in claim 151:

wherein a liquid alloy is formed from said gas reactant and said catalytic liquid; and

wherein said first segment forms upon saturation of said liquid alloy with a species of said gas reactant.

153. A method as recited in 151, wherein said catalytic liquid is formed from a preformed metal colloid.

154. A method as recited in 153, wherein said metal colloid is part of a population of metal colloids with a substantially monodisperse distribution of diameters.

155. A method of fabricating a nanowire, comprising:

forming a first segment by dissolving a first gas reactant in a catalytic liquid followed by growth of a first material;

forming a second segment joined to said first segment by dissolving a second gas reactant in said catalytic liquid followed by growth of a second material joined to said first material;

wherein each said segment forms upon saturation of said liquid alloy with a species of said corresponding gas reactant; and

coating at least a portion of at least one of said segments with a third material to form a third segment;

wherein at least two of said materials are compositionally different; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

156. A method of fabricating a nanowire, comprising:

dissolving a first gas reactant in a catalytic liquid followed by growth of a first segment of material;

dissolving a second gas reactant in said catalytic liquid followed by growth of a second segment of material joined to said first segment; and

dissolving a third gas reactant in said catalytic liquid followed by growth of a third segment of material joined to said second segment;

wherein, said first, second and third segments are longitudinally adjacent;

wherein said second segment is positioned between said first and third segments;

wherein at least two of said segments comprise compositionally different materials; and

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

157. A method as recited in claim 156:

wherein at least two of said gas reactants are the same; and

wherein at least two of said segments comprise the same material.

158. A method as recited in claim 156:

wherein a liquid alloy is formed from each said gas reactant and said catalytic liquid; and

wherein each said nanowire segment forms upon saturation of said liquid alloy with a species of said corresponding gas reactant.

159. A method as recited in claim 156:

wherein at least one of said gas reactants comprises a vapor generated by laser ablation of a growth species; and

wherein at least one of said nanowire segments comprises a combination of species in said laser generated vapor and at least one other gas reactant.

160. A method of fabricating a nanowire heterostructure, comprising:

dissolving a first gas reactant in a catalytic liquid followed by growth of a first segment of a first material; and

dissolving a second gas reactant in said catalytic liquid followed by growth of a second segment of compositionally different second material longitudinally adjacent to said first material;

wherein said second gas reactant comprises a vapor generated by laser ablation of a growth species;

wherein a compositionally dissimilar liquid alloy is formed from each said gas reactant and said catalytic liquid; and

wherein each said segment forms upon saturation of said liquid alloy with a species of said corresponding gas reactant;

wherein said second material comprises a combination of said species in said first and second gas reactants;

and wherein at lest one of said segments has a substantially uniform diameter of less than approximately 200 nm.

161. A method of fabricating a nanowire, comprising:

dissolving a first gas reactant in a catalytic liquid followed by growth of a first segment of a first material;

sequentially laser ablating a growth species in the presence of said first gas reactant thereby forming a second gas reactant;

dissolving said second gas reactant in said catalytic liquid followed by growth of a second segment of a compositionally different second material longitudinally adjacent to said first material;

wherein said second material comprises a combination of species in said first and second gas reactants;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

162. A method as recited in claim 161:

wherein a compositionally dissimilar liquid alloy is formed from each said gas reactant and said catalytic liquid; and

wherein each said segment forms upon saturation of said liquid alloy with a species of said corresponding gas reactant.

163. A method of fabricating a doped semiconductor superlattice nanowire, comprising:

introducing a gas reactant into a reaction chamber of a furnace containing a substrate coated with a reactant metal;

heating said reaction chamber to a temperature at which said metal on said substrate liquefies into at least one droplet;

dissolving said gas reactant into said liquid droplet until saturation where nucleation and growth of a first segment; and

dissolving a dopant and said gas reactant into said liquid droplet until saturation wherein nucleation and growth of a doped second segment occurs on said first segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

167. A method as recited in claim 163:

wherein said substrate comprises silicon; and

wherein said metal comprises gold.

170. A method of fabricating an Si/SiGe superlattice nanowire heterostructure, comprising:

depositing Au on a substrate;

placing said substrate inside a quartz furnace reaction tube;

introducing a gas reactant mixture of H₂ and SiCl₄ into said reaction tube;

heating said reaction tube to a temperature at which said Au liquefies into at least one nanosized droplet of an Au—

Si alloy; and

dissolving said gas reactant into said liquid droplet until saturation where nucleation and growth of a Si segment occurs;

during said Si growth process, generating a Ge vapor through ablation of a Ge target with a laser;

depositing both Ge and Si species into said Au—

Si alloy droplets until saturation wherein nucleation and growth of a SiGe segment occurs on said Si segment;

wherein at least one of said segments has a substantially uniform diameter of less than approximately 200 nm.

200. A laser, comprising:

a nanowire having a substantially uniform diameter of less than approximately 200 nm; and

a pumping source.

201. A laser as recited in claim 200, wherein said nanowire comprises a plurality of segments of compositionally different materials.

202. A laser as recited in claim 200, wherein said pumping source is configured for exciting a population inversion in said nanowire.

203. A laser as recited in claim 200, additionally comprising a support material;

wherein said support material is selected from the group consisting essentially of a solid support material, a liquid support material, a polymer support material, a glassy support material, and a substrate material.

204. A laser as recited in claim 200, further comprising a laser cavity.

205. A laser as recited in claim 204, wherein said cavity is contained within said nanowire.

206. A laser as recited in claim 204, wherein said nanowire has ends that function as reflectors in said cavity.

207. A laser as recited in claim 200, wherein said pumping source is selected from the group consisting essentially of an optical source, an electrical source, a thermal source, an energy transfer source, a plasma source, a laser, and a flash-lamp.

208. A laser as recited in claim 200:

wherein said nanowire comprises a coaxial heterostructure nanowire having a core and sheath; and

wherein said pumping source is an electrical source in which current flows between said core and said sheath.

209. A laser as recited in claim 208, wherein said coaxial heterostructure nanowire represents a p-n junction.

210. A laser as recited in claim 208, wherein an electrical contact is made to said core and an electrical contact is made to said sheath.

211. A laser as recited in claim 208:

wherein said nanowire comprises a longitudinal heterostructure nanowire; and

wherein said pumping source is an electrical source in which current flows between one segments of said longitudinal heterostructure nanowire.

212. A laser as recited in claim 211, wherein said longitudinal heterostructure nanowire represents a p-n junction.

226. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said nanowire comprises a substantially crystalline material.

227. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said substantially crystalline material is substantially monocrystalline.

228. A laser as recited in claim 200, 213, 216, 217, 220, 223 or 225, wherein said nanowire has a diameter ranging from approximately 5 nm to approximately 50 nm.

229. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein the diameter of said nanowire does not vary by more than approximately 10% over the length of said nanowire.

230. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said nanowire comprises a material selected from the group of elements consisting essentially of group II, group III, group IV, group V, and group VI elements, and tertiaries and quaternaries thereof.

231. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said nanowire is embedded in a polymer matrix.

232. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said nanowire is an element of an array of nanowires.

235. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225, wherein said pumping source comprises an electrical pumping source.

246. A laser as recited in claim 200, 213, 215, 216, 217, 220, 223 or 225:

wherein said nanowire has first and second ends; and

wherein said first and second ends have reflective surfaces.

213. A laser, comprising:

a plurality of longitudinally adjacent segments of compositionally different materials forming a nanowire;

at least one of said segments having a substantially uniform diameter of less than approximately 200 nm; and

a pumping source.

214. A nanolaser as recited in claim 213, wherein said pumping source is configured for exciting a population inversion in nanowire.

215. A laser, comprising:

a nanowire with substantially faceted ends with a flat face oriented substantially normal to the longitudinal growth axis of said nanowire, having a substantially uniform diameter of less than approximately 200 nm; and

a pumping source.

216. A laser, comprising:

a plurality of longitudinally adjacent segments of compositionally different materials forming a nanowire;

at least one of said segments having a substantially uniform diameter of less than approximately 200 nm; and

a pumping source for exciting a population inversion in said nanowire.

217. A laser, comprising:

a nanowire having a substantially uniform diameter of less than approximately 200 nm; and

a pumping source;

wherein emission from said laser is directed away from said nanowire in a direction parallel to the longitudinal axis of said nanowire.

218. A laser as recited in claim 217, wherein said nanowire is an element in an array of nanowires.

219. A laser as recited in claim 218:

wherein said nanowires in said array are aligned in substantially the same direction; and

wherein laser emission from said array is directed in a direction substantially parallel to said wires in said array.

220. A laser, comprising:

a nanowire having a substantially uniform diameter of less than approximately 200 nm;

a plurality of quantum dots disposed in said nanowire; and

a pumping source.

221. A laser as recited in claim 220, wherein said nanowire comprises a plurality of segments of compositionally different materials.

222. A laser as recited in claim 220, wherein said pumping source is configured for exciting a population inversion in said quantum dots.

224. A laser as recited in claim 223, wherein said pumping source is configured for exciting a population inversion in said quantum dots.

233. A laser as recited in claim 238, 251, 253, 254, 255, 258, 261 or 263, wherein said pumping source comprises an optical pumping source.

234. A laser as recited in claim 233, wherein said optical pumping source comprises an pumping laser.

236. A laser as recited in claim 235, wherein said electrical pumping source comprises an anode and a cathode.

237. A laser as recited in claim 236, wherein said anode is electrically connected to said nanowire.

238. A laser as recited in claim 237, wherein said electrical connection comprises an ohmic contact.

239. A laser as recited in claim 237, wherein said electrical connection comprises a direct contact.

240. A laser as recited in claim 236, wherein said cathode is electrically connected to said nanowire.

241. A laser as recited in claim 240, wherein said electrical connection comprises an ohmic contact.

242. A laser as recited in claim 240, wherein said electrical connection comprises a direct contact.

243. A laser as recited in claim 236, wherein said anode and said cathode are electrically connected to said nanowire.

244. A laser as recited in claim 243, wherein said electrical connection comprises an ohmic contact.

245. A laser as recited in claim 243, wherein said electrical connection comprises a direct contact.

247. A laser as recited in claim 246, wherein said nanowire comprises a cavity.

249. A laser as recited in claim 248, wherein said nanostructure is embedded in a polymer matrix.

250. A laser as recited in claim 248, wherein said nanostructure is an element of an array of nanostructures.

251. A laser as recited in claim 248, further comprising a pumping source.

252. A laser as recited in claim 251, wherein said pumping source comprises an optical pumping source.

253. A laser as recited in claim 252, wherein said optical pumping source comprises an pumping laser.

254. A laser as recited in claim 251, wherein said pumping source comprises an electrical pumping source.

255. A laser as recited in claim 254, wherein said electrical pumping source comprises an anode and a cathode.

256. A laser as recited in claim 255, wherein said anode is electrically connected to said nanostructure.

257. A laser as recited in claim 255, wherein said cathode is electrically connected to said nanostructure.

258. A laser as recited in claim 255, wherein said anode and said cathode are electrically connected to said nanostructure.

259. A laser as recited in claim 256, 257 or 258, wherein said electrical connection comprises an ohmic contact.

260. A laser as recited in claim 256, 267 or 258, wherein said electrical connection comprises a direct contact.

262. A laser cavity as recited in claim 261, wherein said semiconductor structure comprises a nanowire.

223. A laser, comprising:

a plurality of longitudinally adjacent segments of compositionally different materials forming a nanowire;

at least one of said segments having a substantially uniform diameter of less than approximately 200 nm;

a plurality of quantum dots disposed in said nanowire; and

a pumping source.

225. A laser, comprising:

a plurality of longitudinally adjacent segments of compositionally different materials forming a nanowire;

at least one of said segments having a substantially uniform diameter of less than approximately 200 nm;

a plurality of quantum dots disposed in said nanowire; and

a pumping source for exciting a population inversion in said quantum dots.

248. A laser, comprising:

a multi-faceted, single-crystalline, ZnO nanostructure having a substantially uniform diameter of less than approximately 200 nm;

said nanostructure having first and second ends;

said first end comprising an epitaxial interface between said nanostructure and a sapphire substrate from which said nanostructure extends;

said first and second ends having corresponding reflective faces;

wherein said nanostructure functions as a resonant cavity between said end faces.

261. A laser cavity, comprising:

a semiconductor structure capable of exhibiting quantum confinement effects;

wherein said semiconductor structure comprises a laser cavity.