Germanium nanowire field-effect transistors with SiO2 and high-κ HfO2 gate dielectrics

Single-crystal Ge nanowires are synthesized by a low-temperature (275 °C) chemical vapor deposition (CVD) method. Boron doped p-type GeNW field-effect transistors (FETs) with back-gates and thin ${\mathrm{SiO}}_2$ (10 nm) gate insulators are constructed. Hole mobility higher than 600 cm²/V s is observed in these devices, suggesting high quality and excellent electrical properties of as-grown Ge wires. In addition, integration of high-κ ${\mathrm{HfO}}_2$ (12 nm) gate dielectric into nanowire FETs with top-gates is accomplished with promising device characteristics obtained. The nanowire synthesis and device fabrication steps are all performed below 400 °C, opening a possibility of building three-dimensional electronics with CVD-derived Ge nanowires.