Following Charge Carrier Transport in Freestanding Core–Shell GaN Nanowires on <i>n</i>-Si(111) Substrates

Well-defined heterojunctions inside nanostructured device structures are a basic requirement for any nanoscale device design with advanced electrical properties. For the evaluation of the desired functionalities on the nanoscale, a study of the electrical behavior with appropriate spatial resolution is highly revealing. We specifically address GaN-based core–shell heterostructures and perform multiprobe measurements with ultrahigh spatial resolution. The n+-GaN nanowire core exhibits favorable electrical conductivity, and the behavior of charge carrier transport at a n+-nonintentionally doped -n+-doped core–shell double heterojunction is demonstrated when applying an electron beam-induced current mode. This investigation offers direct insights into the selective charge carrier transport, and therefore into the rectifying junction within the core–shell GaN nanowire, and contributes to a model of the conductivity channels. This experimental approach is crucial for any future advancement of device structures that incorporate bottom-up-grown, heterostructure core–shell GaN nanowires on conductive Si(111) substrates.