Stabilization of unstable and metastable InP native oxide thin films by interface effects

Abstract

III-V semiconductor - oxide interfaces have attracted huge interest due to their substantial potential in electronic applications. However, due to the extreme complexity of the modeling of the interfaces, there are only few ab initio studies of these interfaces.Several model interfaces of native InPO4 oxides are designed in this study. It is shown that energies of the (quasi-)coherent interfaces are much smaller than energies of the incoherent interfaces. Furthermore, it is pointed out that the interface energy can stabilize oxide structures not found in bulk form. Relatively small strain energy and configurational match imply a small interface energy.It is estimated that the gap state density of the In-terminated quasi-coherent interfaces is small or zero. However, partial oxidation of the substrate P atoms, which can be induced, e.g., by non-stoichiometry of the oxide, causes distinct gap states. This is a mechanism to explain Fermi level pinning of the III-V – oxide interfaces. Non-stoichiometric compositions are also investigated. Experimental results on InP native oxide growth are discussed. The models can be used to study various properties of the interfaces and more complex models including, e.g., dislocations or non-planar surfaces can be based on the models.