Geometric structure and electronic properties of wurtzite GaN/HfO2 interface: A first-principles study

Abstract

III-V interface with high-k oxide, especially HfO2, is crucial to the development of high mobility microelectronic devices. In this work, we systematically investigated the wurtzite GaN/cubic HfO2 interface based on the first-principles calculations with density functional theory in terms of the geometric structure and electronic properties. In order to mimic the high-k growth conditions, the interfacial oxygen contents in the slab interface models varied to study the interface stability and the relevant electronic structures. It is found that the oxygen rich interface, i.e., oxygen content of 83.3% (O5), shows the most stability in a large range of the oxygen chemical potential from 0 eV to −4.34 eV. Through the calculations of local density of states and Bader charge analysis, we noticed that increasing the interfacial oxygen content leads to the increase of the valence band offset (VBO) and the decrease of the conduction band offset (CBO), respectively. More importantly, interface O5 displays a promising VBO (0.86 eV) and CBO (1.34 eV), which meets the industrial requirements to confine the carrier in the III-V channel materials. Furthermore, no interfacial gap states are observed in interface O5, indicating that O5 is free of Fermi level pinning. This theoretical exploration suggests that varying oxygen content at the interface could result in the optimal interface for the applications of high mobility electronic devices.