Determination of densities and energy levels of donors in free-standing undoped 3C–SiC epilayers with thicknesses of 80μm

Abstract

The densities and energy levels of donors in free-standing undoped 3C–SiC epilayers with the thicknesses of ∼80μm are investigated from the temperature dependence of the electron concentration n(T) obtained by Hall-effect measurements. Although in the analysis of n(T) many researchers usually assume that only one type of donor species is included in n-type 3C–SiC, no one knows whether this assumption is correct or not. In order to determine the densities and energy levels using n(T) without any assumptions regarding donor species, the graphical peak analysis method called free carrier concentration spectroscopy is applied. Three types of donor species are detected in these epilayers. These donor densities can be reduced to <5×1015cm−3 by growing 3C–SiC epilayers on undulant Si substrate. Moreover, the dependence of each donor level on a total donor density is investigated, which is used in 3C–SiC device simulation.