Schottky-barrier model nonlinear in surface-state concentration and calculation of the I–V characteristics of diodes based on SiC and its solid solutions in the composite charge-transport model

A modified Schottky-barrier model, which is nonlinear in terms of the surface-state concentration and contains a local quasi-Fermi level at the interface induced by excess surface charge, is proposed. Such an approach makes it possible to explain the observed similarity of the I–V characteristics of diodes with the Schottky barrier M/(SiC)$_{1-x}$(AlN)$_{x}$ and those of heterojunctions based on SiC and its solid solutions taking into account $\Phi_g\approx\Phi_{\operatorname{B}}$. The results of calculations of the Schottky-barrier heights are consistent with the experimental data obtained from measurements of the photocurrent for metals (M): Al, Ti, Cr, and Ni. The I–V characteristics in the composite–additive model of charge transport agree with the experimental data for the $n$-M/$p$-(SiC)$_{1-x}$(AlN)$_{x}$ and $n$-6$H$-SiC/$p$-(SiC)$_{0.85}$(AlN)$_{0.15}$ systems.