Carrier Transport in Axial Silicon-Germanium Nanowire Heterojunctions

Recent advances in forming semiconductor heterojunctions within nanowires (NWs) show that the known limitations in the lattice-mismatched hetero-growth should be reconsidered. In this work, we produced axial Si-Ge heterojunction NWs and analyzed their structural and electrical properties. The observed non-linear and rectifying current-voltage characteristics, strong flicker noise and damped current oscillations with frequencies of 20-30 MHz are explained using the proposed SiGe heterojunction NW energy band diagram including energy states associated with the NW near-surface structural imperfections revealed by transmission electron microscopy.