METHOD FOR HETEROEPITAXIAL GROWTH OF III METAL-FACE POLARITY III-NITRIDES ON SUBSTRATES WITH DIAMOND CRYSTAL STRUCTURE AND III-NITRIDE SEMICONDUCTORS

• US 20150144954A1
• Filed: 04/24/2013
• Published: 05/28/2015
• Est. Priority Date: 04/25/2012
• Status: Active Grant

• Current Assignee: Foundation For Research & Technology
• Original Assignee: Foundation For Research & Technology
• Inventors: Georgakilas, Alexandros, Aretouli, Kleopatra, Tsagaraki, Katerina
• Granted Patent: US 10,192,737 B2
• Time in Patent Office: Days
• US Class Current: 257/76
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/02304 formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
• CPC Class Codes: H01L 21/02315 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/02373 Group 14 semiconducting materials
• CPC Class Codes: H01L 21/02376 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02428 Structure
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/02516 Crystal orientation
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/02645 Seed materials
• CPC Class Codes: H01L 21/02661 In-situ cleaning
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/7786 with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT

Abstract

The present invention discloses a method of heteroepitaxial growth enabling the successful growth of thin films of GaN and III-nitride semiconductor heterostructures of (0001) orientation with III metal-face polarity on diamond substrates being either polycrystalline or single crystal with various crystallographic orientations. The method uses a thin AlN nucleation layer on the diamond substrate with thickness equal or less than 5 nm, grown by Molecular Beam Epitaxy (MBE) using a nitrogen plasma source. The invention enables the development of very high power metal-face III-nitride devices, such as High Electron Mobility Transistors, on single crystal or polycrystalline diamond substrates. The method is also applicable for other element IV substrates with diamond crystal structure.

Claims

1-16. -16. (canceled)

17. A method of heteroepitaxial growth of III-Nitride semiconductors on a substrate achieving (0001) orientation and metal-face polarity for a first nucleation layer and the subsequent layers, comprising the following steps:

utilizing an N₂ gas plasma source for epitaxy to deposit an Al-face polarity (0001) AlN nucleation layer less than 5 nm in deposited layer thickness to minimize degradation of the epitaxial growth of the AlN layer and inversion of its polarity;

depositing said AlN layer on a substrate independent of the crystalline surface orientation of said substrate, said substrate being selected from the group of a single-crystal diamond, a polycrystalline diamond, silicon, germanium or an alloy with chemical formula Si_xC_yGe<sub>1−

(x+y)</sub>, whereby 0≦

x, y≦

1, 0≦

x+y≦

1 and x or y less than 0.5; and

by the cooperation between said utilizing an N₂ gas plasma source for epitaxy and said depositing of said AlN layer less than 5 nm thickness, enabling the subsequent depositing on said AlN layer of one or more additional layers while preserving said (0001) orientation and III metal-face polarity.

18. The method according to claim 17, further comprising:

said substrate being any one of a single-crystal diamond or polycrystalline diamond.

19. The method according to claim 18, further comprising:

exposing said substrate to active nitrogen species produced by a nitrogen plasma source before the growth of said AlN layer.

20. The method according to claim 17, further comprising:

between steps of depositing of said AlN layer and overgrowing of said layer by a III-nitride compound layer, exposing said AlN layer to active nitrogen species produced by a nitrogen plasma source.

21. The method according to claim 20, further comprising:

said III-nitride compound layer being a GaN layer.

22. The method according to claim 21, further comprising:

said overgrowing by said GaN layer being carried out by Molecular Beam Epitaxy (MBE) using a solid evaporation source for the Ga beam, maintaining the temperature of said substrate at 710±

40°

C. and maintaining the Ga/N flux ratio in a range of 1.5±

0.5, where the flux of N atoms corresponds to said active nitrogen species produced by a nitrogen plasma source and which flux of N atoms are incident on said substrate.

23. The method according claim 17, further comprising:

overgrowing said AlN layer by a III-Nitride compound layer, and overgrowing said III-Nitride compound layer by at least one layer of a III-Nitride compound.

24. The method according to claim 23, further comprising:

between said overgrowing of said layers of said one or more III-Nitride compounds, interrupting said overgrowing and during said interrupting, exposing the surface of at least one of said layers to active nitrogen species produced by a nitrogen plasma source.

25. The method according to claim 17, further comprising:

utilizing for the growth of said AlN layer Molecular Beam Epitaxy (MBE) using a solid evaporation source for the beam of Al, and maintaining the temperature of said substrate at 800±

50°

C.;

utilizing an Al/N flux ratio equal to 1.0±

0.1, where the flux of N atoms corresponds to the active nitrogen species produced by said plasma source and which flux of N atoms is incident on the substrate; and

depositing by said solid evaporation source a thickness of said AlN layer equal to 1.7±

0.1 nm.

26. The method according claim 17, further comprising:

said AlN layer being less than 3.5 nm.

27. A III-Nitride semiconductor device comprising:

a substrate, said substrate being selected from the group of a single-crystal diamond, a polycrystalline diamond, silicon, germanium or an alloy with chemical type Si_xC_yGe<sub>1−

(x+y)</sub>, whereby 0≦

x, y≦

1, 0≦

x+y≦

1 and x or y less than 0.5;

an Al-face polarity (0001) AlN nucleation layer on said substrate having a thickness of less than 5 nm; and

at least one III-Nitride compound layer over said AlN layer, said cooperation resulting in (0001) orientation and III metal-face polarity.

28. The III-Nitride semiconductor device according to claim 27, further comprising:

said substrate being selected from the group of single-crystal diamond or polycrystalline diamond.

29. The III-Nitride semiconductor device according to claim 27, further comprising:

said III-Nitride compound layer being a GaN layer.

30. The III-Nitride semiconductor device according to claim 28, further comprising:

said III-Nitride compound layer being a GaN layer.

31. The III-Nitride semiconductor device according to claim 27, further comprising:

said AlN layer having a thickness of 1.7±

0.1 nm.

32. The III-Nitride semiconductor device according to claim 27, further comprising:

said AlN layer having a thickness of less than 3.5 nm.

33. A III-Nitride semiconductor device according to claim 27, further comprising:

having at least two layers of compounds selected from the group of III-Nitride compounds over said AlN layer.

34. A III-Nitride semiconductor device comprising:

a substrate, said substrate being a polycrystalline diamond;

an Al-face polarity (0001) AlN nucleation layer on said substrate having a thickness of less than 5 nm; and

at least one III-Nitride compound layer over said AlN layer, said cooperation resulting in (0001) orientation and III metal-face polarity.

35. The III-Nitride semiconductor device according to claim 34, further comprising:

said III-Nitride compound layer being a GaN layer.

36. The III-Nitride semiconductor device according to claim 34, further comprising:

said AlN layer having a thickness of less than 3.5 nm.