Growth of InN on Ge(1 1 1) by molecular beam epitaxy using a GaN buffer

Many novel applications are foreseen for the InN-containing materials especially when cheap, conductive substrates can be used. In this paper, we report on the growth of pure InN layers on germanium (Ge) (1 1 1) substrates. We found that high-quality InN can be grown on Ge(1 1 1) with plasma-assisted molecular beam epitaxy when using a thin GaN intermediate layer. On such intermediate GaN layers, 50 nm InN layers were grown and analyzed by RHEED, XRD, AFM, Hall and I–V measurements. Additionally, using ellipsometry we could determine that the optical bandgap of these InN layers lies around 0.85 eV. Our results indicate that Ge(1 1 1) is a promising substrate for vertical conducting devices, with In(Ga)N on top.