Passivation of interfacial defects at III-V oxide interfaces

The electronic structure of gap states has been calculated in order to assign the interface states observed at III-V oxide interfaces. It is found that As-As dimers and Ga and As dangling bonds can give rise to gap states. The difficulty of passivating interface gap states in III-V oxide interfaces is attributed to an auto-compensation process of defect creation which is activated when an electron counting rule is not satisfied. It is pointed out that oxide deposition needs to avoid burying As dimer states from the free surface, and to avoid sub-surface oxidation during growth or annealing, in order to avoid defect states at the interface or in the subsurface semiconductor.