Doped aluminum nitride crystals and methods of making them

• US 8,747,552 B2
• Filed: 12/18/2009
• Issued: 06/10/2014
• Est. Priority Date: 12/02/2005
• Status: Active Grant

• Current Assignee: Crystal IS, Inc. (Asahi Kasei Corporation)
• Original Assignee: Crystal IS, Inc. (Asahi Kasei Corporation)
• Inventors: Slack, Glen A., Schowalter, Leo J.
• Primary Examiner(s): Kunemund, Bob M
• Application Number:
  US12/642,182
• Publication Number:
  US 20100187541A1
• Time in Patent Office: 1,635 Days
• Field of Search: 117/81, 117/82, 117/83, 117/95, 117/2
• US Class Current: 117/81
• CPC Class Codes: C30B 23/00 Single-crystal growth by condensing evaporated or sublimed materials
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/2258 Diffusion into or out of AIIIBV compounds
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/207 further characterised by the doping material H01L29/2006 takes precedence
• CPC Class Codes: H01L 33/325 characterised by the doping materials

Abstract

Fabrication of doped AlN crystals and/or AlGaN epitaxial layers with high conductivity and mobility is accomplished by, for example, forming mixed crystals including a plurality of impurity species and electrically activating at least a portion of the crystal.

Claims

1. A bi-doped AlN crystal having a thickness of at least approximately 0.1 mm, a diameter of at least approximately 1 cm, and an n-type conductivity greater than approximately 10⁻

5 Ω

<sup>−

1</sup>cm<sup>−

1</sup> at room temperature, the bi-doped AlN crystal being doped with both (i) a donor species comprising Si and (ii) an acceptor species comprising at least one of Mg, Be, or Zn.

2. The AlN crystal of claim 1, wherein the conductivity is greater than approximately 3×

10<sup>−

3</sup> Ω

<sup>−

1</sup>cm<sup>−

1</sup> at room temperature.

3. The AlN crystal of claim 1, wherein a mobility thereof is greater than approximately 25cm² V⁻

1 s<sup>−

1</sup> at room temperature.

4. The AlN crystal of claim 1, wherein a diameter thereof is at least approximately 2 cm.

11. The AlN crystal of claim 1, wherein the donor species and the acceptor species are present at approximately equal concentrations.

12. The AlN crystal of claim 1, wherein the AlN crystal is disposed within a semiconductor device.

5. A bi-doped, p-type AlN crystal having a mobility greater than approximately 25 cm² V⁻

1 s<sup>−

1</sup> at room temperature, the bi-doped AlN crystal being doped with both (i) a donor species comprising O and (ii) an acceptor species comprising C, wherein both the donor species and the acceptor species occupy anion lattice sites in the AlN crystal.

13. The AlN crystal of claim 5, wherein the donor species and the acceptor species are present at approximately equal concentrations

14. The AlN crystal of claim 5, wherein the AlN crystal is disposed within a semiconductor device.

6. A bi-doped, single-crystal AlN structure having dimensions of at least 2mm by 2 mm by 1 mm and a conductivity greater than approximately 10⁻

5 Ω

<sup>−

1</sup>cm<sup>−

1</sup> at room temperature, the bi-doped AlN structure being doped with both (i) a donor species comprising at least one of Si or O and (ii) an acceptor species comprising at least one of Mg, Be, C, or Zn, wherein the donor species and the acceptor species are present at approximately equal concentrations.

15. The AlN structure of claim 6, wherein the AlN structure is disposed within a semiconductor device.

7. A bi-doped AlN crystal doped with both (i) an interstitial dopant species comprising Li and (ii) a substitutional dopant species comprising at least one of Be, Mg, or Zn.

8. The AlN crystal of claim 7, wherein the AlN crystal is substantially intrinsic with a conductivity less than approximately 10⁻

2 Ω

<sup>−

1</sup>cm<sup>−

1</sup> at room temperature.

9. The AlN crystal of claim 7, wherein the interstitial dopant species and the substitutional dopant species are present at approximately equal concentrations.

10. The AlN crystal of claim 7, wherein at least a portion of the interstitial dopant species is extractable via at least one of annealing, immersing the AlN crystal in molten metal, and applying a voltage to at least a portion of the AlN crystal.

16. The AlN crystal of claim 7, wherein the AlN crystal is disposed within a semiconductor device.