Printed Assemblies of Ultrathin, Microscale Inorganic Light Emitting Diodes for Deformable and Semitransparent Displays

• US 20100317132A1
• Filed: 05/12/2010
• Published: 12/16/2010
• Est. Priority Date: 05/12/2009
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Park, Sang Il, Brueckner, Eric, Kim, Hoon-sik, Kim, Rak Hwan, Nuzzo, Ralph, Rogers, John A.
• Granted Patent: US 8,865,489 B2
• Time in Patent Office: Days
• US Class Current: 438/27
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68322 Auxiliary support including means facilitating the selective separation of some of a plurality of devices from the auxiliary support
• CPC Class Codes: H01L 2221/6835 used as a support during build up manufacturing of active devices
• CPC Class Codes: H01L 2221/68354 used to support diced chips prior to mounting
• CPC Class Codes: H01L 2221/68363 used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate
• CPC Class Codes: H01L 2221/68368 used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
• CPC Class Codes: H01L 2221/68386 Separation by peeling
• CPC Class Codes: H01L 2224/8312 Aligning
• CPC Class Codes: H01L 2224/83868 Infrared [IR] curing
• CPC Class Codes: H01L 2224/83871 Visible light curing
• CPC Class Codes: H01L 2224/83874 Ultraviolet [UV] curing
• CPC Class Codes: H01L 2224/95001 involving a temporary auxiliary member not forming part of the bonding apparatus, e.g. removable or sacrificial coating, film or substrate
• CPC Class Codes: H01L 2224/95085 being a liquid, e.g. for fluidic self-assembly
• CPC Class Codes: H01L 24/83 using a layer connector
• CPC Class Codes: H01L 24/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/50 Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• 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
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/05432 Al2O3
• CPC Class Codes: H01L 2924/06 : Polymers polymers per se C08; polymer adhesives C09J
• CPC Class Codes: H01L 2924/12033 : Gunn diode
• CPC Class Codes: H01L 2924/12036 : PN diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12043 : Photo diode
• CPC Class Codes: H01L 2924/13063 : Metal-Semiconductor Field-Effect Transistor [MESFET]
• CPC Class Codes: H01L 2924/13064 : High Electron Mobility Transistor [HEMT, HFET [heterostructure FET], MODFET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/15788 : Glasses, e.g. amorphous oxides, nitrides or fluorides
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/2064 : larger or equal to 1 micron less than 100 microns
• CPC Class Codes: H01L 2924/20641 : larger or equal to 100 microns less than 200 microns
• CPC Class Codes: H01L 2933/0041 : relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 : relating to encapsulations
• CPC Class Codes: H01L 33/0093 : Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/507 : the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: Y10S 438/977 : Thinning or removal of substrate

Abstract

Described herein are printable structures and methods for making, assembling and arranging electronic devices. A number of the methods described herein are useful for assembling electronic devices where one or more device components are embedded in a polymer which is patterned during the embedding process with trenches for electrical interconnects between device components. Some methods described herein are useful for assembling electronic devices by printing methods, such as by dry transfer contact printing methods. Also described herein are GaN light emitting diodes and methods for making and arranging GaN light emitting diodes, for example for display or lighting systems.

Claims

1. A method for making an electronic device, said method comprising the steps of:

providing a growth substrate having a receiving surface;

forming a semiconductor epilayer on said receiving surface via epitaxial growth, said semiconductor epilayer having a first contact surface;

bonding said first contact surface of said semiconductor epilayer to a handle substrate;

releasing said semiconductor epilayer from said growth substrate wherein said semiconductor epilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said semiconductor epilayer;

patterning said second contact surface of said semiconductor epilayer with a mask, thereby generating exposed regions and one or more masked regions of said second contact surface;

removing material from said exposed regions by etching said exposed regions, thereby generating one or more semiconductor structures supported by said handle substrate;

at least partially releasing said one or more semiconductor structures from said handle substrate; and

transferring at least one of said one or more semiconductor structures from said handle substrate to a device substrate via dry transfer contact printing, thereby assembling said semiconductor structures on said device substrate to make said electronic device.

7. The method of claim 1, wherein said growth substrate and said semiconductor epilayer are lattice matched.

8. The method of claim 7, wherein said growth substrate and said semiconductor epilayer are lattice matched to within ±

3.4%.

9. The method of claim 1, wherein said semiconductor epilayer is selected from the group consisting of:

a GaN layer, an InGaN layer, a GaAsN layer, an AlGaN layer, an AlGaAsN layer, a GaAs layer, an InGaAs layer, an AlGaAs layer, an AlGaAsP layer, a GaAsSbN layer and an InN layer; and

wherein said growth substrate is selected from the group consisting of;

sapphire, Si (111), SiC, ZnO, Si (100), MgAl₂O₄ (100), MgAl₂O₄ (111), A-plane sapphire, M-plane sapphire, AlN, MnO, ZrB₂, LiGaO₂, (La,Sr)(Al,Ta)O₃, LiAlO₂, GaAs and InP.

10. The method of claim 1, wherein said semiconductor epilayer has a thickness selected from the range of 1 μ

m to 5 μ

m.

11. The method of claim 1, wherein said semiconductor epilayer is a multilayer comprising a plurality of semiconductor layers having different compositions, doping or both.

12. The method of claim 11, wherein said semiconductor epilayer is a multilayer comprising at least one p-type semiconductor layer in electrical contact with at least one n-type semiconductor layer.

13. The method of claim 11, wherein said multilayer comprises a plurality of LED device layers selected from the group consisting of:

contact layers, spreader layers, cladding layers and barrier layers.

14. The method of claim 11, wherein said multilayer comprises a plurality of GaN layers having different doping, thicknesses or both.

15. The method of claim 11, wherein said multilayer comprises at least one p-type GaN layer in electrical contact with at least one n-type GaN layer.

16. The method of claim 11, wherein said multilayer comprises a plurality of GaN layers selected from the group consisting of:

InGaN, GaN, AlGaN, GaN;

Mg, GaN;

Si, GaN;

AlN and GaN;

ZnO.

17. The method of claim 11, wherein said multilayer comprises a plurality of GaN layers corresponding to a vertical type GaN LED.

18. The method of claim 1, wherein said handle substrate comprises silicon, said semiconductor epilayer comprises GaN and wherein said step of bonding said first contact surface of said semiconductor epilayer to said handle substrate comprises contacting said first contact surface of said semiconductor epilayer to an external surface of said handle substrate so as to establish Van der Waals bonding between said semiconductor epilayer and said handle substrate.

19. The method of claim 1, wherein said step of bonding said first contact surface of said semiconductor epilayer to said handle substrate comprises contacting said first contact surface of said epilayer to an external surface of said handle substrate having an adhesion layer provided thereon.

20. The method of claim 19, wherein said adhesion layer is selected from the group consisting of:

Au, Al, Pd, In, Ni, polyurethane, polyimide, silicone and any combination of these.

21. The method of claim 1, wherein said step of at least partially releasing said semiconductor epilayer from said growth substrate comprises at least partially removing a sacrificial layer provided between said growth substrate and said semiconductor epilayer.

22. The method of claim 21, wherein said sacrificial layer is removed by etching or dissolving said sacrificial layer.

23. The method of claim 22, wherein said sacrificial layer is removed by electrochemical etching.

24. The method of claim 22, wherein said sacrificial layer is removed by photoelectrochemical etching.

25. The method of claim 21, wherein said semiconductor epilayer comprises GaN, said growth substrate comprises sapphire, and said sacrificial layer comprises SiO₂, AlAs, Si₃N₄, ZnO, AlN, HfN or AlInN.

26. The method of claim 1, wherein said semiconductor epilayer and said growth substrate meet at an interface and wherein said step of releasing said semiconductor epilayer from said growth substrate comprises exposing said interface to electromagnetic radiation.

27. The method of claim 26, wherein said electromagnetic radiation is passed through said growth substrate.

28. The method of claim 26, wherein said semiconductor epilayer is GaN and said growth substrate is sapphire and wherein said electromagnetic radiation comprises electromagnetic radiation from a laser.

29. The method of claim 26, further comprising providing an absorbing layer at said interface, wherein said electromagnetic radiation is at least partially absorbed by said absorbing layer, thereby releasing said semiconductor epilayer from said growth substrate.

30. The method of claim 1, wherein said mask comprises a first mask layer of Si₃N₄ provided on at least a portion of said second contact surface of said epilayer and a second mask layer of metal provided on said first mask layer.

31. The method of claim 1, wherein said step of removing material from said exposed regions comprises etching said exposed regions via inductively coupled plasma reactive ion etching.

32. The method of claim 1, further comprising a step of anchoring said one or more semiconductor structures to said handle substrate by at least one homogenous anchor or at least one heterogeneous anchor.

33. The method of claim 1, wherein said step of transferring comprises transferring at least a one of said semiconductor structures from said handle substrate to a device substrate via contact printing using a conformal transfer device.

34. The method of claim 33, wherein said step of transferring comprises transferring at least one of said semiconductor structures from said handle substrate to a device substrate using a PDMS stamp.

35. The method of claim 1, wherein said device substrate is a glass substrate or a polymer substrate.

36. The method of claim 1, wherein said device substrate is a flexible substrate, a large area substrate, a pre-metalized substrate, a substrate pre-patterned with one or more device components or any combination of these.

37. The method of claim 1, wherein said handle substrate comprises a material selected from the group consisting of:

a doped or undoped semiconductor;

a single crystal material, a polycrystalline material, a ceramic, SiC, Si₃N₄, fused silica, alumina (Al₂O₃), ZrO₂, MgO, pyrolytic Boron nitride (PBN), aluminum nitride, aluminum silicate, titania, a polymer, glass, quartz, a semiconductor with or without a thermal oxide layer and any combination of these.

2. A method of making an electronic device, the method comprising the steps of:

providing a growth substrate having a receiving surface;

forming a semiconductor epilayer on said receiving surface via epitaxial growth, said semiconductor epilayer having a first contact surface;

bonding said first contact surface of said semiconductor epilayer to a handle substrate;

releasing said semiconductor epilayer from said growth substrate, wherein at least a portion of said semiconductor epilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said semiconductor epilayer;

processing said semiconductor epilayer on said handle substrate, thereby generating one or more semiconductor structures supported by said handle substrate;

transferring at least one of said one or more semiconductor structures from said handle substrate to a device substrate via dry transfer contact printing, thereby assembling said semiconductor structures on said device substrate to make said electronic device.

4. The method of claim 2, wherein said step of processing a semiconductor epilayer on said handle substrate comprises a processing method selected from the group consisting of:

a patterning process, a growth process, a polishing process, a deposition process, an implantation process, an etching process, an annealing process, a molding process, a curing process, a coating process and any combination of these.

5. The method of claim 2, wherein said step of processing a semiconductor epilayer on said handle substrate comprises forming one or more ohmic contacts on said semiconductor epilayer.

6. The method of claim 2, wherein said step of processing a semiconductor epilayer on said handle substrate comprises forming one or more thermal management structures on said semiconductor epilayer.

38. The method of claim 2, further comprising a step of processing said semiconductor epilayer on said growth substrate.

39. The method of claim 38, wherein said step of processing said semiconductor epilayer on said handle substrate comprises a processing method selected from the group consisting of:

a patterning process, a growth process, a polishing process, a deposition process, an implantation process, an etching process, an annealing process, a molding process, a curing process, a coating process and any combination of these.

3. A method of making an electronic device, the method comprising the steps of:

providing a first growth substrate having a first receiving surface;

forming a first semiconductor epilayer on said first receiving surface via epitaxial growth, said first semiconductor epilayer having a first contact surface;

bonding said first contact surface of said first semiconductor epilayer to a handle substrate;

releasing said first semiconductor epilayer from said first growth substrate, wherein at least a portion of said first semiconductor epilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said first semiconductor epilayer;

providing a second growth substrate having a second receiving surface;

forming a second semiconductor epilayer on said second receiving surface via epitaxial growth;

said second semiconductor epilayer having a third contact surface;

bonding said third contact surface of said second semiconductor epilayer to said handle substrate, said first semiconductor epilayer or both;

releasing said second semiconductor epilayer from said second growth substrate, wherein at least a portion of said second semiconductor epilayer remains bonded to said handle substrate, said first semiconductor epilayer or both, thereby exposing a fourth contact surface of said second semiconductor epilayer;

processing said first semiconductor epilayer, said second semiconductor epilayer or both said first and said second semiconductor epilayers on said handle substrate, thereby generating one or more semiconductor structures supported by said handle substrate;

transferring at least one of said one or more semiconductor structures from said handle substrate to a device substrate via dry transfer contact printing, thereby assembling said semiconductor structures on said device substrate to make said electronic device.

40. A method for making an array of LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

forming a GaN epilayer on said receiving surface via epitaxial growth;

wherein said GaN epilayer is a multilayer comprising at least one p-doped GaN semiconductor layer in electrical contact with at least one n-doped GaN semiconductor layer, said GaN multilayer having a first contact surface;

bonding said first contact surface of said GaN multilayer to a handle substrate;

releasing said GaN multilayer from said growth substrate, wherein said GaN multilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said GaN multilayer;

patterning said second contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said second contact surface;

removing material from said exposed regions by etching said exposed regions, thereby generating one or more LED device structures supported by said handle substrate;

at least partially releasing said one or more LED device structures from said handle substrate; and

transferring at least a portion of said one or more LED device structures from said handle substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

76. The method of claim 40, wherein said GaN multilayer comprises at least one p-type GaN layer, at least one n-type GaN layer and a quantum well region comprising an InGaN layer positioned between said p-type GaN layer and said n-type GaN layer.

77. The method of claim 76, further comprising the steps of:

depositing a metal film on an exposed region of said p-type GaN layer or said n-type GaN layer; and

annealing said metal film;

thereby forming an electrical contact on said p-type GaN layer or said n-type GaN layer.

78. The method of claim 76, further comprising the steps of:

etching a portion of said GaN multilayer so as to expose a region of said n-type GaN layer or said p-type GaN layer;

depositing a metal film on said exposed region of said n-type GaN layer or said p-type GaN layer; and

annealing said metal film, thereby forming an electrical contact on said n-type GaN layer or said p-type GaN layer.

79. The method of claim 40, wherein said GaN multilayer comprises a plurality of GaN layers selected from the group consisting of:

GaN contact layers, GaN spreader layers, GaN cladding layers, GaN barrier layers, GaN etch block layers and GaN buffer layers.

80. The method of claim 40, wherein said LED device structures correspond to a vertical type LED.

81. The method of claim 40, wherein said step of removing material comprises etching said exposed regions via inductively coupled plasma reactive ion etching.

82. The method of claim 40, wherein said mask comprises a first mask layer of Si₃N₄ provided on a portion of said external surface of said GaN multilayer.

83. The method of claim 82, wherein said mask further comprises a second mask layer of metal provided on said first mask layer.

84. The method of claim 40, further comprising a step of anchoring said LED device structures by at least one homogenous anchor or at least one heterogeneous anchor.

85. The method of claim 40, wherein said transferring step comprises transferring at least a portion of said one or more LED device structures to a device substrate via contact printing using a conformal transfer device.

86. The method of claim 85, wherein said transferring step comprises transferring at least a portion of said one or more LED device structures to a device substrate via contact printing using a PDMS stamp.

87. The method of claim 40, wherein said device substrate is a glass substrate or a polymer substrate.

88. The method of claim 40, wherein said device substrate is a flexible substrate, a large area substrate, a pre-metalized substrate, a substrate pre-patterned with one or more device components or any combination of these.

89. The method of claim 40, further comprising a step of removing at least a portion of said mask.

90. The method of claim 40, wherein said device substrate comprises one or more additional LED device structures and said step of transferring at least a portion of said one or more LED device structures comprises printing at least one of said one or more LED device structures on top of said one or more additional LED device structures.

91. The method of claim 40, further comprising a step of printing one or more additional LED device structures on top of said one or more LED device structures on said device substrate.

92. The method of claim 40, further comprising the steps of:

providing one or more metallic contacts in electrical contact with a portion of said one or more LED device structures;

coating said one or more LED device structures and one or more metallic contacts with a photosensitive polymer layer; and

exposing portions of said photosensitive polymer layer to electromagnetic radiation, wherein said electromagnetic radiation is at least partially transmitted through said device substrate and wherein said one or more metallic contacts block at least a portion of said electromagnetic radiation from reaching at least a portion of said photosensitive polymer layer, said one or more metallic contacts thereby serving as one or more self-aligned mask elements.

93. The method of claim 92, further comprising a step of removing portions of said photosensitive polymer layer which are masked by said one or more metallic contacts serving as self-aligned mask elements.

94. The method of claim 93, wherein said step of removing portions of said photosensitive polymer layer which are masked by said one or more metallic contacts serving as self-aligned mask elements comprises developing said photosensitive polymer layer, wherein regions of the photosensitive polymer layer that were not exposed to said electromagnetic radiation are dissolved by exposure to a solvent.

95. The method of claim 40, wherein said step of at least partially releasing said one or more LED device structures comprises photoelectrochemically or electrochemically etching at least a portion of said GaN multilayer.

96. The method of claim 40, further comprising a step of printing phosphors over at least a portion of said array of LEDs.

97. The method of claim 96, wherein said phosphors are printed over said array of LEDs via a contact printing method.

41. A method for making an array of LEDs, said method comprising the steps of:

providing a silicon growth substrate having a (111) orientation and having a receiving surface;

generating a GaN multilayer on said receiving surface of said growth substrate via epitaxial growth, said GaN multilayer comprising at least one p-type GaN layer in electrical contact with at least one n-type GaN layer, said GaN multilayer having a contact surface;

patterning said contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said GaN multilayer;

removing material from said exposed regions by etching said exposed regions and into said growth substrate, thereby exposing a portion of said growth substrate and generating one or more LED device structures;

at least partially releasing said one or more LED device structures from said growth substrate by anisotropic etching said exposed portion of said growth substrate; and

transferring at least a portion of said one or more LED device structures from said growth substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

42. The method of claim 41, wherein said step of removing material etches a depth into said growth substrate greater than or equal to 5 nm.

43. The method of claim 41, wherein said step of removing material etches an average depth into said growth substrate selected from the range of 5 nm to 10 μ

m.

44. The method of claim 41, wherein said anisotropic etching occurs preferentially along <

110>

directions of said growth substrate.

45. The method of claim 41, wherein said anisotropic etching comprises directional wet etching using an anisotropic etchant.

46. The method of claim 45, wherein said anisotropic etchant is potassium hydroxide or tetramethylammonium hydroxide (TMAH).

47. The method of claim 41 wherein said step of removing material from said exposed regions exposes sides walls of said LED device structures, said method further comprising masking at least a portion of said side walls prior to said step of at least partially releasing said LED device structures from said growth substrate.

48. A method for making an array of LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

providing a sacrificial layer on said receiving surface of said growth substrate;

generating a GaN multilayer on said sacrificial layer via epitaxial growth, said GaN multilayer comprising at least one p-type GaN layer in electrical contact with at least one n-type GaN layer, said GaN multilayer having a contact surface;

patterning said contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said GaN multilayer;

removing material from said exposed regions by etching said exposed regions, thereby exposing a portion of said sacrificial layer and generating one or more LED device structures;

at least partially releasing said one or more LED device structures from said growth substrate by removing at least a portion of said sacrificial layer using directional etching, electrochemical etching or photoelectrochemical etching; and

transferring at least a portion of said one or more LED device structures from said growth substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

49. The method of claim 48, wherein said sacrificial layer comprises SiO₂, AlAs, Si₃N₄, ZnO, AlN, HfN or AlInN.

50. The method of claim 48, wherein a buffer layer or an etch block layer is provided between said GaN multilayer and said sacrificial layer.

51. The method of claim 50 wherein said buffer layer or said etch block layer comprises GaN.

52. The method of claim 48, wherein said step of at least partially releasing comprises exposing said sacrificial layer to a selective etchant.

53. The method of claim 52, wherein said selective etchant is HCl, HF, H₃PO₄, potassium hydroxide, tetramethylammonium hydroxide, ethylenediamine, pyrcatechol, hydrazine chelating amines, 1,2-diaminoethane, NaOH or any combination of these.

54. The method of claim 52, wherein said releasing step comprises exposing said sacrificial layer to electromagnetic radiation having wavelengths selected over the range of 100 nm to 800 nm.

55. The method of claim 54, wherein said sacrificial layer is exposed to electromagnetic radiation from a xenon lamp.

56. The method of claim 54 further comprising passing said electromagnetic radiation through an undoped GaN film prior to exposing said sacrificial layer, thereby optically filtering said electromagnetic radiation to remove at least a portion of electromagnetic radiation absorbed by said undoped GaN film.

57. The method of claim 48, wherein said releasing step comprises providing said sacrificial layer at an electric potential selected over the range of 600 mV to 800 mV.

58. The method of claim 48, wherein said GaN multilayer is grown on a sacrificial layer comprising ZnO and wherein said step of at least partially releasing comprises etching said sacrificial layer with NH₄Cl etchant.

59. A method for making an array of LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

generating a GaN multilayer on said sapphire growth substrate via epitaxial growth, said GaN multilayer comprising at least one p-type GaN layer in electrical contact with at least one n-type GaN layer, said GaN multilayer having a first contact surface, wherein said GaN multilayer and said sapphire growth substrate meet at an interface;

bonding said first contact surface of said GaN multilayer to a handle substrate;

exposing said interface between said GaN multilayer and said sapphire growth substrate to electromagnetic radiation;

releasing said GaN multilayer from said growth substrate wherein said GaN multilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said GaN multilayer;

patterning said second contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said GaN multilayer;

removing material from said exposed regions by etching said exposed region, thereby generating one or more LED device structures;

at least partially releasing said one or more LED device structures from said handle substrate; and

transferring at least a portion of said one or more LED device structures from said handle substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

60. The method of claim 59, wherein said interface is exposed to electromagnetic radiation from a laser.

61. The method of claim 59, wherein said interface is exposed to electromagnetic radiation passing through said sapphire growth substrate.

62. The method of claim 59, wherein said handle substrate comprises an external metal film, wherein said first contact surface of said GaN multilayer is contacted with said external metal film of said handle substrate, thereby bonding said GaN multilayer to said handle substrate.

63. The method of claim 62, wherein said external metal film of said handle substrate reflects said electromagnetic radiation, thereby exposing said interface to said electromagnetic radiation.

64. A method for making an array of LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

providing a sacrificial layer on said receiving surface of said sapphire growth substrate;

providing an etch block layer on said sacrificial layer;

generating a GaN multilayer on said etch block layer via epitaxial growth, said GaN multilayer comprising at least one p-type GaN layer in electrical contact with at least one n-type GaN layer, said GaN multilayer having a contact surface;

patterning said contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said GaN multilayer;

removing material from said exposed regions by etching said exposed regions, thereby exposing a portion of said sacrificial layer and generating one or more LED device structures;

at least partially releasing said one or more LED device structures from said growth substrate by removing at least a portion of said sacrificial layer using directional etching, electrochemical etching or photoelectrochemical etching; and

transferring at least a portion of said one or more LED device structures from said growth substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

65. The method of claim 64, wherein said sacrificial layer comprises SiO₂, AlAs, Si₃N₄, ZnO, AlN, HfN or AlInN.

66. The method of claim 64 wherein said etch block layer comprises GaN.

67. The method of claim 66, wherein said etch block layer is generated via epitaxial growth.

68. The method of claim 64, wherein said step of at least partially releasing comprises exposing said sacrificial layer to a selective etchant.

69. The method of claim 68, wherein said selective etchant is HCl, HF, H₃PO₄, potassium hydroxide, tetramethylammonium hydroxide, ethylenediamine, pyrcatechol, hydrazine chelating amines, 1,2-diaminoethane, NaOH or any combination of these.

70. The method of claim 64, wherein said releasing step comprises exposing said sacrificial layer to electromagnetic radiation having wavelengths selected over the range of 100 nm to 800 nm.

71. The method of claim 70, wherein said sacrificial layer is exposed to electromagnetic radiation from a xenon lamp.

72. The method of claim 70 further comprising passing said electromagnetic radiation through an undoped GaN film prior to exposing said sacrificial layer, thereby optically filtering said electromagnetic radiation to remove at least a portion of electromagnetic radiation absorbed by said undoped GaN film.

73. The method of claim 64, wherein said releasing step comprises providing said sacrificial layer at an electric potential selected over the range of 600 mV to 800 mV.

74. A method for making an array of stacked LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

forming a GaN epilayer on said receiving surface via epitaxial growth, wherein said GaN epilayer is a multilayer comprising at least one p-doped GaN semiconductor layer in electrical contact with at least one n-doped GaN semiconductor layer, said GaN multilayer having a first contact surface;

bonding said first contact surface of said GaN multilayer to a handle substrate;

releasing said GaN multilayer from said growth substrate, wherein said GaN multilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said GaN multilayer;

patterning said second contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said second contact surface;

removing material from said exposed regions by etching said exposed regions, thereby generating one or more LED device structures supported by said handle substrate;

at least partially releasing said one or more LED device structures from said handle substrate;

transferring at least a portion of said one or more LED device structures from said handle substrate to a device substrate via dry transfer contact printing, thereby making an array of LED device structures; and

transferring one or more additional LED device structures on top of at least a portion of the array of LED device structures, thereby making said array of stacked LEDs.

75. A method for making an array of stacked LEDs, said method comprising the steps of:

providing a sapphire growth substrate having a receiving surface;

forming a GaN epilayer on said receiving surface via epitaxial growth;

wherein said GaN epilayer is a multilayer comprising at least one p-doped GaN semiconductor layer in electrical contact with at least one n-doped GaN semiconductor layer, said GaN multilayer having a first contact surface;

bonding said first contact surface of said GaN multilayer to a handle substrate;

releasing said GaN multilayer from said growth substrate wherein said GaN multilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said GaN multilayer;

patterning said second contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said second contact surface;

removing material from said exposed regions by etching said exposed regions, thereby generating one or more LED device structures supported by said handle substrate;

at least partially releasing said one or more LED device structures from said handle substrate;

transferring at least a portion of said one or more LED device structures from said handle substrate to a device substrate via dry transfer contact printing, wherein said device substrate comprises an array of LED device structures and said transferring step transfers said one or more LED device structures on top of at least a portion of said array of LED device structures, thereby making said array of stacked LEDs.

98. A method of making a semiconductor device, the method comprising the steps of:

providing a transparent substrate;

assembling a semiconductor device on a surface of said transparent substrate via dry transfer contact printing;

providing one or more metallic contacts in electrical contact with said semiconductor device;

coating said semiconductor device and one or more metallic contacts with a photosensitive polymer layer;

exposing portions of said photosensitive polymer layer to electromagnetic radiation, wherein said electromagnetic radiation is at least partially transmitted through said transparent substrate and wherein said one or more metallic contacts block at least a portion of said electromagnetic radiation from reaching at least a portion of said photosensitive polymer layer, said one or more metallic contacts thereby serving as one or more self-aligned mask elements.

99. The method of claim 98, further comprising a step of removing portions of said photosensitive polymer layer which are masked by said one or more metallic contacts serving as self-aligned mask elements.

100. The method of claim 99, wherein said step of removing portions of said photosensitive polymer layer which are masked by said one or more metallic contacts serving as self-aligned mask elements comprises developing said photosensitive polymer layer and wherein regions of the photosensitive polymer layer that were not exposed to said electromagnetic radiation are dissolved by exposure to a solvent.

101. The method claim 98, wherein said transparent substrate comprises a material selected from the group consisting of:

glass, quartz, sapphire, PET, mylar, PDMS, kapton, polycarbonate, silicone, polyurethane, ethylene tetrafluoroethylene, diamond and any combination of these

102. The method of claim 98, wherein said electromagnetic radiation has wavelengths selected over the range of 100 nm to 800 nm.

103. The method of claim 98, wherein said semiconductor device transmits at least 1% of said electromagnetic radiation.

104. The method of claim 98, wherein at least a portion of said electromagnetic radiation provided to said transparent substrate is reflected, scattered or absorbed by said one or more metallic contacts.

105. The method of claim 98, wherein at least 50% of said electromagnetic radiation received by said one or more metallic contacts is reflected, scattered or absorbed by said one or more metallic contacts.

106. The method of claim 98, wherein at least 75% of said electromagnetic radiation received by said one or more metallic contacts is reflected, scattered or absorbed by said one or more metallic contacts.

107. The method of claim 98, wherein at least 95% of said electromagnetic radiation received by said one or more metallic contacts is reflected, scattered or absorbed by said one or more metallic contacts.

108. The method of claim 98, wherein each of said one or more metallic contacts comprises a material selected from the group consisting of:

gold, nickel, copper, palladium, platinum, silver, titanium, aluminum, molybdenum and any combination of these.

109. The method of claim 98, wherein each of said one or more metallic contacts has a thickness selected over the range of 4 nm to 10 μ

m.

110. The method of claim 98, wherein said photosensitive polymer layer has a thickness selected from the range of 5 nm to 1 mm.

111. The method of claim 98, wherein said photosensitive polymer is a negative tone photopolymer.

112. The method of claim 98, wherein portions of said photosensitive polymer exposed to electromagnetic radiation are at least partially crosslinked.

113. The method of claim 98, wherein said photosensitive polymer comprises a material selected from the group consisting of:

BCB, SU8, WL-5351, polyurethane, silicon, spin-on-glass, polyimide and any combination of these.

114. The method of claim 98, wherein said semiconductor device comprises a LED, a P-N junction, a thin film transistor, a single junction solar cell, a multi-junction solar cell, a photodiode, a laser, a sensor, a photodiode, an electro-optical device, a CMOS device, a MOSFET device, a MESFET device, a photovoltaic cell, a microelectromechanical device, a nanoelectromechanical device, a HEMT device, a light-emitting transistor or any combination of these.

115. A method for making an array of phosphors, said method comprising the steps of:

molding an elastomer layer with an array of recessed regions;

providing phosphor particles over said elastomer layer, wherein said phosphor particles at least partially fill in said array of recessed regions; and

providing an encapsulation layer over said elastomer layer, wherein said phosphor particles are encapsulated in said array of recessed regions, thereby making said array of phosphors.

117. The method of claim 115, wherein said recessed regions have depths selected over the range of 5 nm to 10 mm.

116. A method for making a packaged array of LEDs, said method comprising the steps of:

molding an elastomer layer with an array of recessed regions;

providing phosphor particles over said elastomer layer, wherein said phosphor particles at least partially fill in said array of recessed regions;

providing an encapsulation layer over said elastomer layer, wherein said phosphor particles are encapsulated in said array of recessed regions, thereby making an array of phosphors; and

laminating said array of phosphors over an array of LED device structures, thereby making said packaged array of LEDs.

118. The method of claim 116, further comprising a step of making said array of LED device structures.

119. The method of claim 118, wherein said step of making said array of LED device structures comprises the steps of:

providing a sapphire growth substrate having a receiving surface;

forming a GaN epilayer on said receiving surface via epitaxial growth;

wherein said GaN epilayer is a multilayer comprising at least one p-doped GaN semiconductor layer in electrical contact with at least one n-doped GaN semiconductor layer, said GaN multilayer having a first contact surface;

bonding said first contact surface of said GaN multilayer to a handle substrate;

releasing said GaN multilayer from said growth substrate, wherein said GaN multilayer remains bonded to said handle substrate, thereby exposing a second contact surface of said GaN multilayer;

patterning said second contact surface of said GaN multilayer with a mask, thereby generating exposed regions and one or more masked regions of said second contact surface;

removing material from said exposed regions by etching said exposed regions, thereby generating one or more LED device structures supported by said handle substrate;

at least partially releasing said one or more LED device structures from said handle substrate; and

transferring at least a portion of said one or more LED device structures from said handle substrate to a device substrate via dry transfer contact printing, thereby making said array of LEDs.

120. The method of claim 116, wherein said step of laminating comprises printing said array of phosphors onto a device substrate comprising an array of LED device structures.

121. A method of making an electronic device, said method comprising the steps of:

providing one or more electronic device components;

contacting said one or more electronic device components with a conformal transfer and molding device, thereby transferring said one or more electronic device components onto said conformal transfer and molding device;

contacting a prepolymer layer disposed over a host substrate with said conformal transfer and molding device having said one or more electronic device components positioned thereon, thereby at least partially embedding said one or more electronic device components into said prepolymer layer and patterning said prepolymer layer with one or more recessed features;

curing said prepolymer layer, thereby forming a polymer layer having one or more recessed features; and

filling at least a portion of said one or more recessed features with a filling material selected from the group consisting of;

a conductive material, an optical material, a heat transfer material and any combination of these.

122. The method of claim 121, wherein said filling step comprises the steps of:

providing a filling material on a surface of said polymer; and

dragging a scraping tool along said surface of said polymer to fill said filling material into at least a portion of said one or more recessed features.

123. The method of claim 121, wherein said host substrate comprises a material selected from the group consisting of:

polymer, glass, plastic, semiconductor, sapphire, ceramic and any combination of these.

124. The method of claim 121, wherein said prepolymer layer comprises a material selected from the group consisting of:

a photocurable polymer, a thermally curable polymer, a photocurable polyurethane, SU8, PDMS, NOA series, photosensitive polyimide, photosensitive silicone and any combination of these.

125. The method of claim 121, wherein said step of curing said prepolymer layer comprises exposing said prepolymer layer to electromagnetic radiation or heating said prepolymer layer.

126. The method of claim 121, further comprising a step of curing said filling material.

127. The method of claim 126, wherein said step of curing said filling material comprises heating said filling material or exposing said filling material to electromagnetic radiation.

128. The method of claim 121, wherein at least one of said one or more electronic device components comprises one or more electrode contacts.

129. The method of claim 128, further comprising a step of etching at least a portion of said polymer to expose said one or more electrode contacts.

130. The method of claim 121, wherein said filling material comprises a conductive material.

131. The method of claim 130, wherein said conductive material provides one or more electrical interconnections to at least one electronic device component.

132. The method of claim 130, wherein said conductive material is in electrical communication with one or more electrode contacts of said one or more electronic device components.

133. The method of claim 130, wherein, after curing, said conductive material has a resistivity selected over the range of 1×

10<sup>−

10</sup> to 1×

10<sup>−

2</sup> Ω

·

cm.

134. The method of claim 130, wherein said conductive material comprises a conductive paste selected from the group consisting of:

silver epoxy, gold epoxy, copper epoxy, aluminum epoxy and any combination of these.

135. The method of claim 121, wherein said filling material comprises an optical material.

136. The method of claim 135, wherein said optical material forms an optical element selected from the group consisting of:

a collecting optic, a concentrating optic, a reflective optic, a diffusing optic, a dispersive optic, a lens, a phosphor, a waveguide, an optical fiber, an optical coating, a transparent optic, an optical filter, a polarizing optic and any combination of these.

137. The method of claim 135, wherein said optical material comprises a material selected from the group consisting of:

polymer, plastic, glass, phosphor and any combination of these.

138. The method of claim 121, wherein at least one of said one or more electronic device components is selected from the group consisting of:

a P—

N junction, a thin film transistor, a single junction solar cell, a multi-junction solar cell, a photodiode, a light emitting diode, a laser, a sensor, a photodiode, an electro-optical device, a CMOS device, a MOSFET device, a MESFET device, a photovoltaic cell, a microelectromechanical device, a HEMT device and any combination of these.

139. The method of claim 121, wherein at least one of said one or more electronic device components has a vertical dimension selected over the range of 10 nm to 10 μ

m.

140. The method of claim 121, wherein at least one of said one or more electronic device components has a lateral dimension selected over the range of 1 μ

m to 10 mm.

141. A method of making an electronic device, said method comprising the steps of:

providing a conformal transfer and molding device having a contact surface comprising one or more transfer surfaces and one or more raised molding features;

contacting one or more electronic device components with said conformal transfer and molding device, thereby positioning said one or more electronic device components on said one or more transfer surfaces of said conformal transfer and molding device;

contacting a prepolymer layer disposed over a host substrate with said conformal transfer and molding device having said one or more electronic device components positioned thereon, thereby at least partially embedding said one or more electronic device components and said one or more raised molding features into said prepolymer layer;

curing said prepolymer layer, thereby forming a polymer layer, wherein said one or more raised molding features of said conformal transfer and molding device are replicated as one or more recessed features in said polymer layer;

separating said conformal transfer and molding device from said polymer layer, wherein said one or more electronic device components are retained in said polymer layer;

applying a filling material to a surface of said polymer layer; and

dragging a scraping tool along said surface of said polymer to fill said filling material into at least a portion of said one or more recessed features.

142. The method of claim 141, wherein said filling material is selected from the group consisting of:

a conductive material, an optical material, a heat transfer material and any combination of these.

143. A method of making an electronic device, said method comprising the steps of:

providing a host substrate with a prepolymer disposed thereon;

at least partially embedding one or more electronic device components into said prepolymer layer, wherein one or more recessed features are patterned in said prepolymer layer during said embedding step;

curing said prepolymer layer, thereby forming a polymer layer having one or more recessed features and fixing said one or more electronic device components in said polymer layer; and

filling at least a portion of said one or more recessed features with a conductive material, wherein said conductive material provides one or more electrical interconnections to at least one electronic device component.

144. A method for making a printable electronic device on a device substrate, said method comprising the steps of:

providing a printable electronic device having a contact area, wherein said printable electronic device is anchored to a host substrate via one or more homogeneous or heterogeneous anchors;

contacting said contact area of said printable electronic device with a contact surface of a conformable transfer device, wherein said contact surface of said conformable transfer device has an area smaller than said contact area of said printable electronic device, and wherein said contact area and said contact surface are aligned off center from each other, wherein contact between said contact surface and said contact area binds said printable electronic device to said contact surface;

separating said printable electronic device and said host substrate, thereby releasing said one or more homogeneous or heterogeneous anchors;

contacting said printable electronic device disposed on said contact surface with a receiving surface of said device substrate; and

separating said contact surface of said conformable transfer device and said printable electronic device, wherein said printable electronic device is transferred onto said receiving surface, thereby assembling said printable electronic device on said receiving surface of said device substrate.

145. The method of claim 144, wherein said contact surface of said conformable transfer device is less than 50% of said contact area of said electronic device.

146. The method of claim 144, wherein said contact surface of said conformable transfer device is 25% to 75% of said contact area of said electronic device.

147. The method of claim 144, wherein said contact area and said contact surface are aligned off center from each other by at least 1 μ

m.

148. The method of claim 144, wherein said contact area and said contact surface are aligned off center from each other by 1 μ

m to 100 μ

m.

149. The method of claim 144, wherein said contact surface is provided on a relief feature of said conformable transfer device.

150. The method of claim 144, wherein said conformable transfer device comprises a plurality of relief features providing a plurality of contact regions;

said method comprising;

providing a plurality of printable electronic devices each having a contact area, wherein each of said printable electronic devices is anchored to a host substrate via one or more homogeneous or heterogeneous anchors;

contacting said contact areas of said printable electronic devices with said contact regions of said conformable transfer device, wherein each of said contact regions of said conformable transfer device has an area smaller than said each of contact areas of said printable electronic device, and wherein said contact areas and said contact regions are aligned off center from each other, wherein contact between said contact regions and said contact areas binds said printable electronic devices to said contact regions;

separating said printable electronic devices and said host substrate, thereby releasing said homogeneous or heterogeneous anchors;

contacting said printable electronic devices disposed on said contact regions with a receiving surface of said device substrate; and

separating said contact surfaces of said conformable transfer device and said printable electronic devices, wherein said printable electronic devices are transferred onto said receiving surface, thereby assembling said printable electronic devices on said receiving surface of said device substrate.

151. The method of claim 144, wherein said conformable transfer device is a PDMS stamp.

152. The method of claim 144, wherein said electronic device is a P—

N junction, a thin film transistor, a single junction solar cell, a multi-junction solar cell, a photodiode, a light emitting diode, a laser, a CMOS device, a MOSFET device, a MESFET device, a photovoltaic cell, a microelectromechanical device, a HEMT device or any combination of these.

153. The method of claim 144, wherein said device substrate is a glass substrate, a polymer substrate, a semiconductor substrate, a metal substrate or a ceramic substrate.

154. The method of claim 144, wherein said device substrate is a flexible substrate, a large area substrate, a pre-metalized substrate, a substrate pre-patterned with one or more device components, or any combination of these.