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 NH 3 . They were found to be depletion mode transistors with an electron concentration of ∼10 7 cm −1 , electron mobility of 50 cm 2 V −1 s −1 , and on/off current ratio of ∼10 2 . Using the transmission line method, the resistivity of the GaN nanowires and specific contact resistivity were estimated to be 7.8 × 10 −2 Ω cm and 1.7 × 10 −5 Ω cm 2 , respectively. The current transport at contacts was described by the thermionic emission with a barrier height of 68 meV. 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.