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

• US 7,919,791 B2
• Filed: 03/25/2002
• Issued: 04/05/2011
• Est. Priority Date: 03/25/2002
• Status: Expired due to Fees

• Current Assignee: Wolfspeed, Inc.
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Brandes, George R., Flynn, Jeffrey S.
• Primary Examiner(s): Jackson, Jr.; Jerome
• Application Number:
  US10/107,001
• Publication Number:
  US 20030178633A1
• Time in Patent Office: 3,298 Days
• Field of Search: 257/194
• US Class Current: 257/194
• 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 high electron mobility transistor (HEMT) having a delta doped layer located in a barrier layer that is adjacent to a channel layer that provides a selectively operable conductive path between a source contact and a drain contact of the HEMT, wherein:

said barrier layer comprises a nitride of a metal or metal alloy that is compositionally different or stoichiometrically different from a nitride of a metal or metal alloy of the channel layer, with the barrier layer having a bandgap greater than a bandgap of the channel layer, and

said delta doped layer and said channel layer are spaced apart by a distance of less than or equal to about 30 Angstroms.

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

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

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

5. The microelectronic device structure of claim 1, wherein said delta doped layer comprises a 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 an AlGaN/GaN HEMT.

7. The microelectronic device structure of claim 1, wherein dopant in the delta doped layer is silicon.

8. 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.

9. The microelectronic device structure of claim 1, wherein the channel layer comprises GaN and the barrier layer comprises A1GaN.

10. The microelectronic device structure of claim 1, wherein the delta doped layer is arranged to improve ohmic contact behavior of a source contact or a drain contact of the HEMT.

11. The microelectronic device structure of claim 1, further comprising a GaN substrate.

12. The microelectronic device structure of claim 1, wherein the barrier layer is undoped except for the presence of the delta doped layer.

13. A microelectronic device structure comprising a high electron mobility transistor (HEMT) including:

a source contact and a drain contact;

a Group III-V nitride channel layer that provides a selectively operable conductive path between the source contact and the drain contact;

a gate element adapted to regulate flow of current through the channel layer; and

a Group III-V nitride barrier layer adjacent to the channel layer, the barrier layer having a bandgap that is greater than a bandgap of the channel layer;

wherein a delta doped layer is defined within the barrier layer, and the delta doped layer is spaced apart from the channel layer by a distance of less than or equal to about 30 Angstroms.

14. The microelectronic device structure of claim 13, wherein the barrier layer comprises a nitride of a metal or metal alloy that is compositionally different or stoichiometrically different from a nitride of a metal or metal alloy of the channel layer.

15. The microelectronic device structure of claim 13, wherein the channel layer comprises GaN and the barrier layer comprises AlGaN.

16. The microelectronic device structure of claim 13, further comprising a GaN substrate.

17. The microelectronic device structure of claim 13, wherein said delta doped layer comprises at least one dopant species selected from the group consisting of Si, Ge, Mg, C, 0, Ca, Zn, Li, Mn, Na, K, Cd, Rb, Sr, Sc and Be.

18. The microelectronic device structure of claim 13, wherein the barrier layer is undoped except for the presence of the delta doped layer.