Conduction-type dependence of thermal oxidation rate on SiC(0001)

Abstract

The conduction-type dependent thermal oxidation rate in SiC was discovered. The oxidation was performed for SiC(0001) with nitrogen doping (n-type) in the range from 2.0×10¹⁶ cm^-3 to 1.0×10¹⁹ cm^-3, and aluminum doping (p-type) in the range from 2.0×10¹⁵ cm^-3 to 1.0×10¹⁹ cm^-3, exhibiting a clear dependence. For n-type SiC the oxide thickness increases for higher doping density, and for p-type the thickness decreases. Note that in the case of Si oxidation, there exists very little difference of oxidation rate between the conduction types in such low doping density, and the dependence is peculiar to SiC. The authors speculate the difference originates from the difference in carrier (electron/hole) density during the oxidation, which can reasonably explain the difference in the oxidation rate between Si and SiC.