One-step synthesis of Ge-SiO2 core-shell nanowires

We report on a one-step process based on thermal evaporation at moderate temperatures that yields single-crystalline Ge nanowires (NWs) encapsulated in SiO2 shells. The dielectric shell forms around the Ge NW core during the NW growth process itself, an advantage in the assembly of NW devices such as surround-gate NW field-effect transistors (FETs). The formation of the core-shell structures proceeds via an unconventional vapor-liquid-solid process involving root growth of SiGe NWs and selective Si oxidation by background oxygen in the reactor. Electrical measurements of the p-type Ge-SiO2 FET devices show efficient gate control and hole mobilities of 20 cm(2)/V s.