O2 alloys*

The GeSnO₂ alloy system is a newly studied ultra-wide bandgap semiconductor with potential applications in power electronics. Recently, interest in these alloys has grown after experimental studies reported that GeSnO₂ alloys can be grown in thin-film form across a broad range of compositions, that they show n-type conductivity, and that Sn-rich alloys exhibit only a small reduction of the electron mobility with increasing Ge composition. In this work, we calculate the thermodynamic and electronic properties of the Ge_xSn_(1-x)O2 alloys with hybrid density functional theory. We investigate the band structures and band alignments as a function of alloy composition, and we identify ordered phases in the phase diagram. Our results shed light on the synthesis, electronic, and transport properties of these novel ultra-wide bandgap semiconductors.