Method for fabricating a P-N heterojunction device utilizing HVPE grown III-V compound layers and resultant device

• US 20030049898A1
• Filed: 08/09/2002
• Published: 03/13/2003
• Est. Priority Date: 11/18/1997
• Status: Active Grant

• Current Assignee: Kyma Technologies, Inc.
• Original Assignee: Technologies And Devices International Inc.
• Inventors: Tsvetkov, Denis, Dmitriev, Vladimir A., Usikov, Alexander, Karpov, Sergey, Helava, Heikki I.
• Granted Patent: US 6,890,809 B2
• Time in Patent Office: Days
• US Class Current: 438/200
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method for fabricating a p-n heterojunction device is provided, the device being preferably comprised of an n-type GaN layer co-doped with silicon and zinc and a p-type AlGaN layer. The device may also include a p-type GaN capping layer. The device can be grown on any of a variety of different base substrates, the base substrate comprised of either a single substrate or a single substrate and an intermediary layer. The device can be grown directly onto the surface of the substrate without the inclusion of a low temperature buffer layer.

Claims

19. A method of fabricating a p-n heterojunction device utilizing HVPE techniques and comprising the steps of:

locating a Ga metal in a first source zone of a reaction chamber;

locating an Al metal in a second source zone of said reaction chamber;

locating at least one acceptor impurity metal in a third source zone of said reaction chamber;

locating a Si source in a fourth source zone of said reaction chamber;

locating a Zn source in a fifth source zone of said reaction chamber;

locating a substrate within a growth zone of said reaction chamber;

heating said substrate to a first temperature, wherein said first temperature is greater than 900°

C.;

heating said Ga metal to a second temperature, wherein said second temperature is in the range of 750°

C. to 1050°

C.;

heating said Al metal to a third temperature, wherein said third temperature is in the range of 700°

C. to 850°

C.;

heating said at least one acceptor impurity metal to a fourth temperature, wherein said fourth temperature is in the range of 250°

C. to 1050°

C.;

introducing a halide reaction gas into said first source zone to form a gallium chloride compound;

introducing said halide reaction gas into said second source zone to form an aluminum trichloride compound;

transporting said gallium chloride compound to said growth zone;

transporting said Si to said growth zone;

transporting said Zn to said growth zone;

introducing a reaction gas into said growth zone, said reaction gas containing nitrogen;

growing an n-type GaN layer on said substrate, said n-type GaN layer formed by said reaction gas reacting with said gallium chloride compound, wherein said n-type GaN layer is co-doped with said Si and said Zn;

transporting said aluminum trichloride compound to said growth zone;

transporting said at least one acceptor impurity metal to said growth zone; and

growing a p-type AlGaN layer on said n-type GaN layer, said p-type AlGaN layer formed by said reaction gas reacting with said gallium chloride compound and said aluminum trichloride compound, wherein said p-type AlGaN layer incorporates said at least one acceptor impurity metal.

1. A III-V p-n heterojunction device, comprising:

a base substrate;

a high temperature n-type GaN layer grown directly on said base substrate, wherein said high temperature n-type GaN layer is grown at a temperature greater than 900°

C. using HVPE techniques, wherein a low temperature buffer layer is not interposed between said base substrate and said high temperature n-type GaN layer, wherein said high temperature n-type GaN layer is co-doped with Si and Zn; and

a p-type AlGaN layer grown on said high temperature n-type GaN layer using HVPE techniques, said p-type AlGaN layer forming a p-n heterojunction with said n-type GaN layer.

2. The III-V p-n heterojunction device of claim 1, wherein said high temperature n-type GaN layer is grown at a temperature greater than 950°

C. using HVPE techniques.

3. The III-V p-n heterojunction device of claim 1, wherein said high temperature n-type GaN layer is grown at a temperature greater than 1000°

C. using HVPE techniques.

4. The III-V p-n heterojunction device of claim 1, wherein said base substrate is comprised of a single substrate.

5. The III-V p-n heterojunction device of claim 4, wherein said single substrate is selected from the group of materials consisting of sapphire, silicon carbide, gallium nitride, and silicon.

6. The III-V p-n heterojunction device of claim 1, wherein said base substrate is comprised of an underlying substrate and an intermediary layer.

7. The III-V p-n heterojunction device of claim 6, wherein said intermediary layer is a nucleation layer.

8. The III-V p-n heterojunction device of claim 6, wherein said underlying substrate is selected from the group of materials consisting of sapphire, silicon carbide, gallium nitride, and silicon and wherein said intermediary layer is comprised of n-type GaN.

9. The III-V p-n heterojunction device of claim 1, further comprising a capping layer grown on said p-type AlGaN layer using HVPE techniques.

10. The III-V p-n heterojunction device of claim 9, wherein said capping layer is comprised of a p-type GaN layer.

11. The III-V p-n heterojunction device of claim 1, further comprising:

a first contact deposited on said p-type AlGaN layer; and

a second contact deposited on said base substrate.

12. The III-V p-n heterojunction device of claim 11, wherein said first and second contacts are selected from the group of materials consisting of nickel, palladium, gold, platinum, gold-nickel, and palladium-platinum.

13. The III-V p-n heterojunction device of claim 9, further comprising:

a first contact deposited on said capping layer; and

a second contact deposited on said base substrate.

14. The III-V p-n heterojunction device of claim 13, wherein said first and second contacts are selected from the group of materials consisting of nickel, palladium, gold, platinum, gold-nickel, and palladium-platinum.

15. The III-V p-n heterojunction device of claim 1, wherein said p-type AlGaN layer includes at least one acceptor impurity metal selected from the group of metals consisting of Mg, Zn, and MgZn.

16. The III-V p-n heterojunction device of claim 15, wherein a concentration of said at least one acceptor impurity metal within said p-type AlGaN layer is in the range of 10¹⁸ to 10²¹ atoms cm⁻

3.

17. The III-V p-n heterojunction device of claim 15, wherein a concentration of said at least one acceptor impurity metal within said p-type AlGaN layer is in the range of 10¹⁹ to 10²⁰ atoms cm⁻

3.

18. The III-V p-n heterojunction device of claim 15, wherein said p-type AlGaN layer is co-doped with O.

20. The method of claim 19, further comprising the steps of:

depositing a first contact on said p-type AlGaN layer; and

depositing a second contact on said substrate.

23. The method of claim 19, further comprising the step of positioning said at least one acceptor impurity metal on a first sapphire boat within said third source zone.

24. The method of claim 23, further comprising the steps of:

positioning said Ga metal on a second sapphire boat within said first source zone; and

positioning said Al metal on a silicon carbide boat within said second source zone.

25. The method of claim 19, further comprising the steps of:

locating a second acceptor impurity metal in a fourth source zone of said reaction chamber;

heating said second acceptor impurity metal to a fifth temperature, wherein said fifth temperature is in the range of 250°

C. to 1050°

C.; and

transporting said second acceptor impurity metal to said growth zone simultaneously with said at least one acceptor impurity metal.

26. The method of claim 25, further comprising positioning said second acceptor impurity metal on a sapphire boat within said fourth source zone.

27. The method of claim 19, further comprising selecting Mg as said at least one acceptor impurity metal.

28. The method of claim 27, wherein said fourth temperature is in the range of 450°

C. to 700°

C.

29. The method of claim 27, wherein said fourth temperature is in the range of 550°

C. to 650°

C.

30. The method of claim 19, further comprising the step of discontinuing said step of transporting said Si to said growth zone, wherein said discontinuing step occurs prior to said step of growing said p-type AlGaN layer on said n-type GaN layer.

32. The method of claim 19, further comprising the step of pre-filling said reaction chamber with a flowing inert gas.

33. The method of claim 19, wherein said first temperature is within the temperature range of 1000°

C. to 1100°

C.

34. The method of claim 19, further comprising the step of annealing said p-type AlGaN layer.

35. The method of claim 34, said annealing step further comprised of the step of heating said p-type AlGaN layer to a temperature within the range of 700°

C. to 800°

C.

36. The method of claim 35, wherein said annealing step is performed in an annealing gas atmosphere, wherein said annealing gas is selected from the group of gases consisting of nitrogen, argon, NH₃, or some combination of nitrogen, argon and NH₃.

37. The method of claim 35, wherein said annealing step is performed for approximately 10 minutes.

38. The method of claim 19, further comprising the step of selecting a transport rate associated with said step of transporting said at least one acceptor impurity metal to said growth zone, wherein said selected transport rate achieves a concentration of said at least one acceptor impurity metal within said p-type AlGaN layer of between 10¹⁸ to 10²¹ atoms cm⁻

3.

39. The method of claim 19, further comprising the step of selecting a transport rate associated with said step of transporting said at least one acceptor impurity metal to said growth zone, wherein said selected transport rate achieves a concentration of said at least one acceptor impurity metal within said p-type AlGaN layer of between 10¹⁹ to 10²⁰ atoms cm⁻

3.

42. The method of claim 19, further comprising the step of preconditioning said reaction chamber.

43. The method of claim 42, wherein said pre-conditioning step is further comprised of saturating said growth zone and said first, second, and third source zones with said at least one acceptor impurity metal.

44. The method of claim 19, further comprising the step of etching said substrate, said Ga metal, said Al metal, and said at least one acceptor impurity metal to remove surface contamination, said etching step performed prior said first growing step.

45. The method of claim 44, wherein said etching step is performed prior to said first transporting step.

46. The method of claim 44, wherein said etching step is performed prior to said first heating step.

47. The method of claim 19, further comprising the step of growing an n-type GaN intermediary layer on said substrate to form a base substrate, wherein said step of growing said n-type GaN intermediary layer is performed prior to said steps of transporting said Si and transporting said Zn to said growth zone.

20-1. The method of claim 19, further comprising the steps of:

discontinuing said step of transporting said aluminum trichloride compound to said growth zone; and

growing a p-type GaN layer on said p-type AlGaN layer, said p-type GaN layer formed by said reaction gas reacting with said gallium chloride compound, wherein said p-type GaN layer incorporates said at least one acceptor impurity metal.

22. The method of claim 21, further comprising the steps of:

depositing a first contact on said p-type GaN layer; and

depositing a second contact on said substrate.

31. The method of claim 21, further comprising the step of discontinuing said step of transporting said Si to said growth zone, wherein said discontinuing step occurs prior to said step of growing said p-type GaN layer on said p-type AlGaN layer.

40. The method of claim 21, further comprising the step of selecting a transport rate associated with said step of transporting said at least one acceptor impurity metal to said growth zone, wherein said selected transport rate achieves a concentration of said at least one acceptor impurity metal within said p-type GaN layer of between 10¹⁸ to 10²¹ atoms cm⁻

3.

41. The method of claim 21 further comprising the step of selecting a transport rate associated with said step of transporting said at least one acceptor impurity metal to said growth zone, wherein said selected transport rate achieves a concentration of said at least one acceptor impurity metal within said p-type GaN layer of between 10¹⁹ to 10²⁰ atoms cm⁻

3.