Program in SiC High Temperature, Hostile-Environment Electronics

The physical and electronic properties of SiC make it the foremost semiconductor material for short wavelength optoelectronic, high temperature, radiation resistant, and high-power/high-frequency electronic devices.  Collectively, these properties allow SiC devices to offer tremendous benefits over other available semiconductor devices in a large number of industrial and military applications.

We have been engaged in SiC high temperature electronics research for several years.  The focus has been on understanding the behavior of the polar surfaces of SiC as a function of temperature, metal coverage, and gas reactivity.  In addition, we have elucidated the oxidation mechanisms of SiC faces at the monolayer level, the growth modes of monolayer coverages of refractory metals on SiC, and the reactive chemistry of SiC during ohmic and Schottky barrier contact formation.

SiC Physical & Electronic Properties

A summary of the most important properties in comparison to Si, GaAs, GaP, and diamond is shown below:

Some of our latest work on SiC surface physics . . .

Monolayer Growth Modes of Re and Nb on the Polar Faces of 4H-SiC

K. W. Bryant and M. J. Bozack

Surface Science Laboratory, Department of Physics, Auburn University, Auburn, AL 36849 (USA)

Abstract: Auger electron spectroscopy (AES) and secondary electron emission has been used to determine how thin monolayer films of Re and Nb grow on the 4H-SiC (C-face) and 4H-SiC (Si-face) surfaces at room temperature.  The secondary electron emission was monitored by the crystal current (SEECC) method and compared to the change in Auger electron peak-to-peak intensities for both substrate and adsorbate.  On the 4H-SiC (Si-face), both metals first form a single monolayer followed by growth of simultaneous monolayers (MSM mode).  On the 4H-SiC(C-face), both metals grow layer-by-layer (Frank-van der Merwe, FM mode).

Surface Composition of 4H-SiC as a Function of Temperature

K. W. Bryant and M. J. Bozack

Surface Science Laboratory, Department of Physics, Auburn University, Auburn, AL 36849 (USA)

Abstract:  We report surface compositions of the 4H-SiC(C-face) and 4H-SiC (Si-face) over the temperature range 300 to 1400 K, studied by Auger electron spectroscopy (AES), energy loss spectroscopy (ELS) and quadrupole mass spectroscopy (QMS). Below 800 K, no significant changes in surface composition are observed.  Between 800 K and 1200 K, silicon preferentially volatilizes, leaving a slightly graphitized surface.  Above 1200 K, preferential volatility of silicon results in a heavily graphitized surface. The thickness of the graphitized layer is greatest on the 4H-SiC(C-face) surface (~ 8 Å @ 1400 K).  Results are compared with earlier work involving the polar faces of 6H-SiC.