Semiconductor conductive layers

• US 7,583,715 B2
• Filed: 06/15/2005
• Issued: 09/01/2009
• Est. Priority Date: 06/15/2004
• Status: Expired due to Fees

• Current Assignee: UNM Rainforest Innovations (f/k/a STC.UNM) (The University of New Mexico)
• Original Assignee: UNM Rainforest Innovations (f/k/a STC.UNM) (The University of New Mexico)
• Inventors: Hill, Peter O., Dawson, Larry R., Dowd, Philip, Krishna, Sanjay
• Primary Examiner(s): Nguyen, Dung T
• Application Number:
  US11/153,245
• Publication Number:
  US 20060027823A1
• Time in Patent Office: 1,539 Days
• Field of Search: 372/45.011, 372/45.012
• US Class Current: 372/45.011
• CPC Class Codes: H01L 33/305 characterised by the doping materials
• CPC Class Codes: H01S 5/20 Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers

Abstract

Structures and methods for electronic devices with improved conductive regions are provided. The conductive region may include digital alloy superlattice structures, which allow higher doping levels to be achieved than for a bulk (random) alloy with the same average composition. Furthermore, the superlattice structures may improve the resistivity of the region, improving the current spreading of the region and hence the electronic properties of electronic devices such as optoelectronic devices.

Claims

1. An electronic device comprising:

a substrate;

a conductive region disposed above the substrate, the conductive region having an average composition of indium aluminum antimonide, the conductive region including a first portion having a doped semiconductor material of a different composition of indium, aluminum, and antimonide from the average composition, the first portion doped to a level higher than a doping level of other portions of the conductive region; and

an active region disposed above the substrate, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the conductive region relative to the substrate.

2. The electronic device of claim 1, wherein the active region is coupled to the conductive region by a waveguiding layer.

3. The electronic device of claim 1, wherein the conductive region has an average composition of In_xAl₁₋

xSb with 0.1<

x<

0.45.

4. The electronic device of claim 3, wherein the first portion include Te-doped In_xAl₁₋

xSb with x<

0.1 or x>

0.45.

5. The electronic device of claim 1, wherein the conductive region and the active region are configured in an edge-emitting laser.

6. The electronic device of claim 1, wherein the active region includes material configured to emit light at a wavelength in range of about 2 μ

m to about 6 μ

m.

7. The electronic device of claim 1, wherein the conductive region includes a second portion having a doped semiconductor material, the second portion doped lower than the first portion, the second portion configured to operatively provide tunneling of carriers from the first portion.

8. An electronic device comprising:

a digital alloy semiconductor superlattice disposed above a substrate, the digital alloy semiconductor superlattice having;

an average composition of indium aluminum antimonide; and

a layer of semiconductor material having a composition of indium, aluminum, and antimonide different from the average composition, the layer of semiconductor material having a doping level higher than a level for other layers of the digital alloy semiconductor superlattice.

9. The electronic device of claim 8, wherein the digital alloy semiconductor provides a conductive layer configured to provide a vertical current path or a lateral current path in the electronic device.

10. The electronic device of claim 8, wherein the digital alloy semiconductor provides a conductive layer configured to provide a vertical current path and a lateral current path in the electronic device.

11. The electronic device of claim 8, wherein the digital alloy semiconductor superlattice is coherently strained.

12. The electronic device of claim 8, wherein the digital alloy semiconductor superlattice is coupled to a light processing layer disposed above the substrate.

13. The electronic device of claim 12, wherein the electronic device includes a buffer disposed on the substrate, the buffer configured to limit defects in materials disposed on the buffer layer.

14. The electronic device of claim 13, wherein the buffer layer includes a second digital alloy semiconductor superlattice.

15. The electronic device of claim 12, wherein the light processing layer includes an active region of a laser.

16. The electronic device of claim 15, wherein the laser includes an edge-emitting laser.

17. The electronic device of claim 15, wherein the laser includes a vertical-cavity surface-emitting diode or a quantum cascade laser.

18. The electronic device of claim 12, wherein the light processing layer includes the light processing layer of a light emitting diode.

19. The electronic device of claim 8, wherein the electronic device includes an optoelectronic device.

20. The electronic device of claim 19, wherein the optoelectronic device includes a mid-wavelength infrared optoelectronic device.

21. The electronic device of claim 19, wherein the optoelectronic device includes a photodetector.

22. The electronic device of claim 19, wherein the optoelectronic device includes a photodiode.

23. The electronic device of claim 19, wherein the optoelectronic device includes a light modulator.

24. The electronic device of claim 8, wherein the digital alloy semiconductor superlattice includes layers of indium aluminum antimonide.

25. The electronic device of claim 8, wherein the digital alloy semiconductor superlattice has an average composition of In_xAl₁₋

xSb with 0.1<

x<

0.45.

26. The electronic device of claim 25, wherein the digital alloy semiconductor superlattice includes a layer of Te-doped In_xAl₁₋

xSb with x<

0.1.

27. The electronic device of claim 25, wherein the digital alloy semiconductor superlattice includes a layer of Te-doped In_xAl₁₋

xSb with x>

0.45.

28. An electronic device comprising:

a digital alloy semiconductor superlattice disposed above a substrate, the digital alloy semiconductor superlattice being an antimonide-based structure, the digital alloy semiconductor superlattice having;

an average composition;

a first layer of semiconductor material having a composition different from the average composition; and

a second layer of semiconductor material, wherein both the first layer of semiconductor material and the second layer of semiconductor material have a doping level higher than a level for other layers of the digital alloy semiconductor superlattice.

29. An electronic device comprising:

a substrate;

a superlattice having an average composition of indium aluminum antimonide, the superlattice having a first layer of doped semiconductor material of a different composition of indium, aluminum, and antimonide from the average composition, the first layer more highly doped than a doping level of other layers of the superlattice; and

an active region, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the superlattice relative to the substrate above which both the active region and the superlattice are disposed.

30. The electronic device of claim 29, wherein the active region is coupled to the superlattice by a waveguiding layer.

31. The electronic device of claim 29, wherein the superlattice and the active region are configured in an edge-emitting laser.

32. The electronic device of claim 29, wherein the active region includes material to emit light at a wavelength in range of about 2 μ

m to about 6 μ

m.

33. The electronic device of claim 29, wherein the superlattice includes a coherently strained digital alloy superlattice.

34. The electronic device of claim 29, wherein the superlattice includes a second layer of doped semiconductor material, the second layer having a doping level lower than that of the first layer, the second layer configured to operatively provide tunneling of carriers from the first layer.

35. The electronic device of claim 29, wherein the superlattice has a plurality of layers of varying composition and thickness to provide varied vertical current flow or lateral current flow throughout the superlattice.

36. The electronic device of claim 29, where the superlattice has an average composition of In_xAl₁₋

xSb with 0.1<

x<

0.45.

37. The electronic device of claim 36, where the superlattice includes a layer of Te-doped In_xAl₁₋

xSb with x<

0.1.

38. The electronic device of claim 36, where the superlattice includes a layer of Te-doped In_xAl₁₋

xSb with x>

0.45.

39. The electronic device of claim 29, where the active region includes a quantum dot.

40. The electronic device of claim 29, where the active region includes a quantum well.

41. An electronic device comprising:

a substrate;

a superlattice having an average composition, the superlattice having a first layer of doped semiconductor material of a different composition from the average composition, the first layer more highly doped than a doping level of other layers of the superlattice;

an active region, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the superlattice relative to the substrate above which both the active region and the superlattice are disposed; and

a conductive layer disposed opposite the superlattice relative to the active region, the conductive layer being another superlattice.

42. An electronic device comprising:

a substrate;

a superlattice having an average composition, the superlattice having a first layer of doped semiconductor material of a different composition from the average composition, the first layer more highly doped than a doping level of other layers of the superlattice, the superlattice having a plurality of layers of varying composition and thickness to provide varied vertical current flow or lateral current flow throughout the superlattice, wherein the plurality of layers are varied to provide in a first section of the superlattice a first lateral current flow higher than a first vertical current flow in the first section and in a second section of the superlattice a second vertical current flow higher than a second lateral current flow in the second section; and

an active region, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the superlattice relative to the substrate above which both the active region and the superlattice are disposed.

43. An electronic device comprising:

a substrate;

a superlattice having an average composition, the superlattice having a first layer of doped semiconductor material of a different composition from the average composition, the first layer more highly doped than a doping level of other layers of the superlattice; and

an active region, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the superlattice relative to the substrate above which both the active region and the superlattice are disposed, wherein the superlattice includes two In_xAl<sub>1−

x</sub>Sb layers, the two In_xAl<sub>1−

x</sub>Sb layers having different compositions from each other.

44. An electronic device comprising:

a substrate;

a superlattice having an average composition, the superlattice having a first layer of doped semiconductor material of a different composition from the average composition, the first layer more highly doped than a doping level of other layers of the superlattice; and

an active region, the active region having material configured to emit light at a desired wavelength of operation, the active region disposed above or below the superlattice relative to the substrate above which both the active region and the superlattice are disposed, wherein the superlattice includes a layer of Te-doped In_xAl<sub>1−

x</sub>Sb.

45. A method including:

forming a conductive region disposed above a substrate, the conductive region having an average composition of indium aluminum antimonide, the conductive region including a first portion having a doped semiconductor material of a composition of indium, aluminum, and antimonide different from the average composition, the first portion doped to a level higher than a doping level of other portions of the conductive region; and

forming an active region disposed above the substrate, the active region having material to emit light at a desired wavelength of operation, the active region disposed above or below the conductive region relative to the substrate.

46. The method of claim 45, wherein forming the conductive region includes forming a superlattice.

47. The method of claim 46, wherein forming a superlattice includes forming the superlattice having an average composition of In_xAl₁₋

xSb with 0.1<

x<

0.45.

48. The method of claim 47, wherein forming the superlattice includes forming a Te-doped In_xAl₁₋

xSb layer with x<

0.1 or x>

0.45.

49. The method of claim 45, wherein the method includes forming a buffer on the substrate coupling the conductive region to the substrate.

50. A method including:

forming a conductive region disposed above a substrate, the conductive region having an average composition, the conductive region including a first portion having a doped semiconductor material of a composition different from the average composition, the first portion doped to a level higher than a doping level of other portions of the conductive region;

forming an active region disposed above the substrate, the active region having material to emit light at a desired wavelength of operation, the active region disposed above or below the conductive region relative to the substrate; and

forming a buffer on the substrate coupling the conductive region to the substrate, wherein forming the buffer includes forming a digital alloy semiconductor superlattice of InAlSb layers.

51. A method including:

forming a conductive region disposed above a substrate, the conductive region having an average composition, the conductive region including a first portion having a doped semiconductor material of a composition different from the average composition, the first portion doped to a level higher than a doping level of other portions of the conductive region;

forming an active region disposed above the substrate, the active region having material to emit light at a desired wavelength of operation, the active region disposed above or below the conductive region relative to the substrate; and

forming a buffer on the substrate coupling the conductive region to the substrate, wherein the method includes;

forming the conductive region as a superlattice;

forming a first cladding layer on the conductive region;

forming a first waveguiding layer on the cladding region with the active region on the waveguiding layer; and

forming a conductive layer above the active region.

52. The method of claim 51, wherein the method includes

etching portions of the conductive layer, the active region, the first waveguiding layer, and the first cladding layer to expose a surface of the conductive region;

and

forming a contact on the surface of the conductive region exposed.

53. An electronic device comprising:

a first superlattice disposed above a substrate, the first superlattice being a conductive region having an average composition of indium aluminum antimonide, the first superlattice including a first layer of a doped semiconductor material having a different composition of indium, aluminum, and antimonide from the average composition, the first layer doped to a level higher than a doping level of the other layers of the first superlattice, the first superlattice having a first conductivity type;

a first cladding layer disposed on the first superlattice;

a first waveguiding layer disposed on the first cladding layer;

an active region disposed on the first waveguiding layer and above the substrate, the active region having material to emit light at a desired wavelength of operation;

a second waveguiding layer disposed on the active region;

a second cladding layer disposed on the second waveguiding layer; and

a conductive layer disposed on the second cladding layer, the conductive layer having a second conductivity type different from the first conductivity type.

54. The electronic device of claim 53, wherein conductive layer includes a second superlattice, the second superlattice including a second layer of a doped semiconductor material, the second layer doped to a level higher than a doping level of the other layers of the second superlattice.

55. The electronic device of claim 53, wherein the active region has material to emit light at a wavelength in a range from about 2 μ

m to about 6 μ

m.

56. The electronic device of claim 53, wherein the electronic device includes:

a buffer layer disposed on the substrate, the buffer layer coupling the substrate to the first superlattice.

57. The electronic device of claim 56, wherein the buffer layer includes material having a lattice constant to limit defects in materials disposed on the buffer layer.

58. The electronic device of claim 56, wherein the buffer layer includes a digital alloy semiconductor superlattice of lnAlSb layers.

59. The electronic device of claim 53, wherein the superlattice includes a digital alloy semiconductor superlattice with InAlSb layers.

60. The electronic device of claim 53, where the superlattice has an average composition of In_xAl₁₋

xSb with 0.1<

x<

0.45 with a layer of Te-doped In_xAl<sub>1−

x</sub>Sb having x<

0.1 or x>

0.45.