Theoretical investigation of the interface fluctuation causing low channel conductivity at SiO2/SiC interfaces through the self-energy and average Green’s function

The low channel mobility and the high interface state density at SiO2/SiC interfaces is quantitatively explained by introducing potential fluctuation at interfaces. The density of states with the perturbation potential is calculated through the self-energy and average Green’s function, and the interface state density is determined by assuming that localized states are interface trap states. The mobility is obtained by using the Fermi’s golden rule, the Boltzmann’s transport equation, and the relaxation time approximation. The parameters characterizing the potential fluctuation is estimated so as to reproduce the mobility (100 cm2V−1s−1) and the interface state density (5.4×1012 cm−2) that was obtained in a previous report by analyzing the experimental results of a MOSFET: the root-mean-square of the potential being more than 0.02 eV and the correlation length being less than few nm.