Low Temperature Deposition and Characterization of N- and P-Type Silicon Carbide Thin Films and Associated Ohmic and Schottky Contacts.
Abstract
Epitaxial, undoped films of 6H-SiC(0001) and 3C-SiC(111) have been grown by gas source (GS) MBE on 6H-SiC(0001) substrates and 2H-AlN(0001) layers between 1050-1250 deg C using SiH4 and C2H4 for Si and C, respectively. Controlled n-and p-type doping was achieved via NH3 and evaporated Al. REED and HRTEM showed the films to be monocrystalline and of either the 6H or 3C polytype. As-deposited (at RT) NiAl contacts with Ni passivating layers on p-type 6H-SiC(0001) substrates were rectifying with very low P( sub L) (approx. 1x10(exp -8) A/sq cm at 10 V), I(sub D) values between 1.4 and 2.4, and a SBH of approx. 1.37 eV. As-deposited (at RT) Ni and Au contacts on p-type 6H-SiC displayed similar C-V characteristics with SBH values of 1.31 and 1.27 eV, respectively. The Fermi level is partially pinned in p-type 6H-SiC. The Ni/NiAl contacts on p+ (1x10(exp-19)/cu cm) 6H-SiC (0001) were ohmic after annealing for 10-80 s at 1000 deg C in a N2 ambient. The estimated specific contact resistivity from a non-mesa etched TLM pattern was 2-3x10(exp -2) W./sq cm. Several boron compounds were selected as alternatives to Al materials. UPS measurements of Al(0.75)Ga(0.25)N films deposited in situ via GSMBE and Si-doped GaN, Al(0.13)Ga(0.87)N and Al(0.55)Ga(0.45)N films deposited ex situ via OMVPE on 6H-SiC(0001) exhibited NEA characteristics in the former material, but not in the latter three samples. Annealing of the Al(0.55)Ga(0.45)N sample to >400 deg C resulted in the disappearance of the sharp emission features. This effect was related to surface contammation. jg p2
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1995
- Accession Number
- ADA302914
Entities
People
- M. C. Benjamin
- Robert F Davis
- Robert J. Nemanich
- S. Fleming
- S. Kern
Organizations
- North Carolina State University