Contact characteristics in GaN nanowire devices

GaN nanowire field-effect transistors were fabricated using single-crystalline GaN nanowires synthesized by thermal evaporation of GaN powder with NH₃. They were found to be depletion mode transistors with an electron concentration of ∼10⁷cm^-1, electron mobility of 50cm²V^-1s^-1, and on/off current ratio of ∼10². Using the transmission line method, the resistivity of the GaN nanowires and specific contact resistivity were estimated to be 7.8 × 10^-2Ωcm and 1.7 × 10 ^-5Ωcm², respectively. The current transport at contacts was described by the thermionic emission with a barrier height of 68meV. The contact characteristics were improved by supplying excess carriers in the nanowires. These results will enable GaN nanowires to be used in reliable nanoscale devices.