Rhenium ohmic contacts on 6H-SiC

Journal Article · Mon Nov 01 00:00:00 EST 2004 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1797550· OSTI ID:20662160

McDaniel, G Y; Fenstermaker, S T; Lampert, W V; Holloway, P H ^[1]

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1. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400 (United States)

Rhenium (Re) thin-film contacts (100-nm thick) were deposited on carbon-rich, nominally stoichiometric, and silicon-rich 6H-SiC surfaces, which were moderately doped with nitrogen (1.28x10{sup 18} cm{sup -3}). Morphology (Dektak), phase formation (x-ray diffraction), chemistry (Auger electron spectroscopy), and electrical properties (I-V) were characterized for the as-deposited and annealed (120 min, 1000 deg. C, vacuum <1x10{sup -6} Torr) contacts. As-deposited films were nonohmic. Films grown on carbon-rich surfaces were nonspecular, granular, and often delaminated during characterization. At room temperature in air, the Re films on stoichiometric SiC remained optically specular reflecting for 3 h, but then became hazy from oxidation. The Re films on silicon-rich surfaces, stored in air at room temperature, resisted ex situ oxidation for approximately 24 h. The annealed samples remained specular without visible signs of oxidation. The annealing resulted in a reduction in surface roughness for all the films regardless of substrate chemistry. The phase separation between carbon and rhenium was observed based on the formation of interfacial Re clusters and a {approx}10-nm graphite surface layer after annealing. Auger data showed that Si layers (5-10 nm) deposited to create Si-rich surfaces were partially consumed to form rhenium silicide during annealing, and the sharp Re/Si/SiC interface became more diffused with Re detected {approx}50 nm deeper into the structure. The annealing of Re films on moderately doped (1.28x10{sup 18} cm{sup -3}) SiC resulted in ohmic contacts with an average specific contact resistance of 7.0x10{sup -5} {omega} cm{sup 2} for stoichiometric and 1.6x10{sup -5} {omega} cm{sup 2} for silicon-rich samples. The annealed contacts on carbon-rich surfaces remained rectifying.

• OSTI ID: 20662160
• Journal Information: Journal of Applied Physics, Vol. 96, Issue 9; Other Information: DOI: 10.1063/1.1797550; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
AUGER ELECTRON SPECTROSCOPY
DEPOSITION
DOPED MATERIALS
ELECTRICAL PROPERTIES
ELECTRON BEAMS
GRAPHITE
INTERFACES
MORPHOLOGY
NITROGEN
OXIDATION
RHENIUM
ROUGHNESS
SEMICONDUCTOR MATERIALS
SILICON CARBIDES
STOICHIOMETRY
SUBSTRATES
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
X-RAY DIFFRACTION