Origin of HfO2/GaAs interface states and interface passivation: A first principles study

First principles calculations of HfO2/GaAs interfaces indicate that the interface states originate from the charge mismatch between HfO2 and GaAs surfaces. We find that a model neutral interface (HfO2 and GaAs surfaces terminated with two O and one Ga atoms per surface unit cell) removes gap states due to the balance of the interface charge. F and H can neutralize the HfO2/GaAs interface resulting in useful band offsets, thus becoming possible candidates to passivate the interface states.