The characteristics of MBE-grown InxAl1−xN/GaN surface states

The density and energy distribution of InxAl1−xN/GaN surface donor states are studied for InxAl1−xN structures with varying indium compositions. The results support a surface states model with a constant energy distribution of 2.17–2.63 eV below the conduction band minimum and a concentration of 4.64–8.27 × 1013 cm−2 eV−1. It is shown that the properties of the surface states are affected by the surface indium composition xs, as opposed to the bulk composition, xb (InxAl1−xN). Higher surface indium composition xs increases the density of surface states and narrows their energy distribution.