Band offsets in c-Si/Si-XII heterojunctions

•Ab initio characterization of a potentially novel device for solar applications.•Estimate band offsets formed at the c-Si/Si-XII heterojunction.•Analyze convergence of Tersoff׳s method for determining the charge neutrality level.

Silicon has a rich phase diagram with a multitude of phases existing over a wide range of pressures and temperatures, in addition to the common cubic silicon (c-Si) phase. One such phase, Si-XII, was first observed less than 2 decades ago in diamond anvil experiments, and more recently as a product of nanoindentation. In some of these latter experiments, I–V measurements were performed to characterize the c-Si/Si-XII interface that results when Si-XII is formed in cubic silicon substrates. In this paper we describe calculations of the band offsets in c-Si/Si-XII heterojunctions. We find that the heterojunction is of Type I and that the band offsets are estimated to be ΔEv=0.3eV and ΔEc=0.5eV for the valence bands and conduction bands, respectively.