Doped group III-V nitride materials, and microelectronic devices and device precursor structures comprising same

• US 20030178633A1
• Filed: 03/25/2002
• Published: 09/25/2003
• Est. Priority Date: 03/25/2002
• Status: Active Grant

• Current Assignee: Wolfspeed, Inc.
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Brandes, George R., Flynn, Jeffrey S.
• Granted Patent: US 7,919,791 B2
• Time in Patent Office: Days
• US Class Current: 257/101
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/365 Planar doping, e.g. atomic-plane doping, delta-doping
• CPC Class Codes: H01L 29/7784 with delta or planar doped donor layer H01L29/7785 takes precedence
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01S 5/305 characterised by the doping materials used in the laser structure
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

A Group III-V nitride microelectronic device structure including a delta doped layer and/or a doped superlattice. A delta doping method is described, including the steps of: depositing semiconductor material on a substrate by a first epitaxial film growth process; terminating the deposition of semiconductor material on the substrate to present an epitaxial film surface; delta doping the semiconductor material at the epitaxial film surface, to form a delta doping layer thereon; terminating the delta doping; resuming deposition of semiconductor material to deposit semiconductor material on the delta doping layer, in a second epitaxial film growth process; and continuing the semiconductor material second epitaxial film growth process to a predetermined extent, to form a doped microelectronic device structure, wherein the delta doping layer is internalized in semiconductor material deposited in the first and second epitaxial film growth processes.

Claims

1. A Group III-V nitride microelectronic device structure comprising a delta doped layer.

2. The microelectronic device structure of claim 1, wherein said delta doped layer is intermediate undoped III-V nitride layers in said device structure

3. The microelectronic device structure of claim 2, wherein said Group III-V nitride layers comprise AlGaN.

4. The microelectronic device structure of claim 2, wherein said Group III-V nitride layers comprise GaN.

5. The microelectronic device structure of claim 1, wherein said delta doped layer comprises at least one dopant species selected from the group consisting of Si, Ge, Mg, C, O, Ca, Zn, Li, Mn, Na, K, Cd, Rb, Sr, Sc and Be.

6. The microelectronic device structure of claim 1, comprising a device structure selected from the group consisting of UV LEDs, AlGaN/GaN high electron mobility transistors (HEMTs), contact structures, isolation structures, AlGaN FETs, optoelectronic transistor detectors, tunnel doped structures, doped base heterojunction bipolar transistors (HBTs), and optical filters.

7. The microelectronic device structure of claim 1, comprising an AlGaN/GaN high electron mobility transistors (HEMT).

8. The microelectronic device structure of claim 7, wherein the AlGaN/GaN high electron mobility transistors (HEMT) comprises a delta doping layer in a barrier layer of the device serving to increase sheet charge in the device structure, in comparison to a corresponding device structure lacking such delta doping layer.

9. The microelectronic device structure of claim 8, wherein the delta doped layer is located in the barrier layer at a position relative to a channel layer of the device structure such that the delta doped layer and the channel layer are spaced apart by a distance that is less than tunneling distance of charge carriers in operation of the device structure.

10. The microelectronic device structure of claim 9, wherein the dop ant in the delta doping layer is silicon.

26. The microelectronic device structure of claim 1, further comprising a substrate formed of a material selected from the group consisting of sapphire, SiC, and GaN.

11. A Group III-V nitride microelectronic device structure including a doped III-V nitride superlattice.

12. The microelectronic device structure of claim 11, wherein said superlattice comprises a GaN or AlGaN superlattice.

13. The microelectronic device structure of claim 11, wherein said superlattice is doped with at least one dopant selected from the group consisting of Si, Ge, Mg, C, O, Ca, Zn, Li, Mn, Na, K, Cd, Rb, Sr, Sc and Be.

14. The microelectronic device structure of claim 11, wherein said superlattice comprises a first and second alloy wherein the bandgap of the second alloy is greater than the bandgap of the first alloy and conductivity is increased relative to a corresponding microelectronic device structure comprising an undoped superlattice.

15. A method of forming a doped Group III-V nitride semiconductor microelectronic device structure, comprising the steps of:

depositing semiconductor material on a substrate by a first epitaxial film growth process;

terminating the deposition of semiconductor material on the substrate to present an epitaxial film surface;

delta doping the semiconductor material at the epitaxial film surface, to form a delta doping layer thereon;

terminating the delta doping;

resuming deposition of semiconductor material to deposit semiconductor material on the delta doping layer, in a second epitaxial film growth process; and

continuing said semiconductor material second epitaxial film growth process to a predetermined extent, to form a doped microelectronic device structure, wherein the delta doping layer is internalized in semiconductor material deposited in said first and second epitaxial film growth processes.

16. The method of claim 15, wherein the delta doping comprises a process selected from the group consisting of MOCVD, MBE, HVPE, PECVD and ion implant.

17. The method of claim 15, wherein the semiconductor material comprises GaN or AlGaN.

18. The method of claim 15, wherein the semiconductor material comprises GaN.

19. The method of claim 15, wherein the semiconductor material comprises AlGaN.

20. The method of claim 15, wherein the delta doping incorporates dopant atoms in Group III sites.

21. The method of claim 15, wherein the delta doping incorporates dopant atoms in Group V sites.

22. The method of claim 15, wherein the delta doping incorporates dopant atoms in interstitial sites of the Group III-V nitride semiconductor.

23. The method of claim 15, wherein the delta doping is conducted under process conditions including the presence of a surfactant.

24. The method of claim 15, wherein the first and second epitaxial growth processes and delta doped layer formation include growth of GaN or AlGaN under process conditions including:

temperature in a range of from about 400°

C. to about 1200°

C., pressure in a range of from about 1 to about 1000 torr, V/III ratio in a range of from about 1 to about 100,000.

25. The method of claim 24, wherein the first and second epitaxial growth processes and delta-doped layer formation are conducted in an ambient comprising nitrogen, hydrogen or ammonia.

42. A doped Group III-V nitride semiconductor microelectronic device structure, formed by the method of claim 15.

44. The method of claim 15, wherein the delta doping comprises a process selected from the group consisting of MOCVD, MBE, HVPE, and PECVD or ion implant.45. A delta doped base for a HBT structure.

27. A HEMT device comprising a sapphire substrate, an AlN buffer layer on the substrate, a GaN layer on the AlN buffer layer, and an AlGaN layer on the GaN layer, wherein the AlGaN layer has a delta doped layer therein.

28. The HEMT device of claim 27, wherein the delta doped layer comprises a dopant selected from the group consisting of Si, Ge, Mg, C, O, Ca, Zn, Li, Mn, Na, K, Cd, Rb, Sr, Sc and Be.

29. The HEMT device of claim 27, wherein the delta doped layer comprises a silicon dopant.

30. A Group III-V nitride HEMT device including a delta doped layer in a barrier layer of the device.

31. The HEMT device according to claim 30, wherein the delta doped layer is in proximity to a channel layer of the device, at a position such that distance between the delta doped layer and the channel layer is less than tunneling distance of charge carriers in operation of the device.

32. A Group III-V nitride optoelectronic device selected from the group consisting of Group III-V nitride emitters, Group III-V nitride detectors and Group III-V nitride filters, and comprising a delta doped layer effective to improve optical characteristics of the device.

33. A Group III-V nitride optoelectronic device comprising a Group III-V nitride semiconductor, and a delta doped layer effective to reduce light sensitivity of the device at energies lower than the bandgap of the Group III-V nitride semiconductor, relative to a corresponding Group III-V nitride optoelectronic device lacking such delta doped layer.

34. A Group III-V nitride semiconductor device, comprising a device layer selected from the group consisting of contact layers, isolation layers and interconnect layers, wherein at least one of said layers is delta doped.

35. The Group III-V nitride semiconductor device of claim 34, wherein the device comprises a HEMT device, wherein the device includes a delta doped contact layer.

36. A Group III-V nitride microelectronic device structure including a doped III-V nitride superlattice, wherein the superlattice comprises three or more alloys.

37. A Group III-V nitride microelectronic device structure including a doped III-V nitride superlattice, wherein the superlattice comprises two alloys defining a first alloy region, and a second alloy region, and the superlattice is delta doped in at least one of said first and second regions.

38. The Group III-V nitride microelectronic device structure of claim 37, wherein one of the first and second regions is doped.

39. The Group III-V nitride microelectronic device structure of claim 37, wherein both of the first and second regions is doped.

40. A Group III-V nitride microelectronic device structure including a quaternary alloy superlattice.

41. A Group III-V nitride photocathode including a p-doped superlattice.

43. A Group III-V nitride microelectronic device structure including a delta doped layer and/or a doped superlattice.

45. A delta doped structured with a substantially enhanced mobility compared with a bulk doped structure.

46. A Group III-V nitride microelectronic device structure comprising two or more delta doped layers.

47. The Group III-V nitride microelectronic device structure of claim 46, comprising a multiplicity of delta doping layers, to control conductivity in the device structure in a predetermined manner.