Bonding and gap states at GaAs-oxide interfaces

The nature of bonding and possible causes of Fermi level pinning at high mobility–high dielectric constant oxide GaAs:HfO2 interfaces are discussed. It is argued that these are atoms with defective bonding, rather than states due to the bulk semiconductor of its interface. Electron-counting rules are used to define interfaces which are insulating, and which can be used in future as hosts for interfaces containing defects.