Interface states in semiconductor and their influence on Schottky barrier in β-Ga2O3

The density of surface and interface states versus Schottky barrier in $\beta$-Ga${}_2$O${}_3$ has been numerically calculated by taking into account of neutrality level, work function, intermediate insulator thickness, and dopant concentration. It was found there exists a critical neutrality level at which interfacial state has the minimum effects on the Schottky barrier. Comparison with experimental observations shows Ohmic contact exhibits a lower neutrality level resulting in the rise of Schottky barrier and Schottky contact has a higher neutrality level leading to the drop of Schottky barrier. The findings indicate Ohmic contact or Schottky contact can be improved if more acceptor type defects or more donor type defects are generated on the interface after treatment respectively.