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 similar to 10(7) cm(-1), electron mobility of 50 cm(2) V-1 s(-1), and on/off current ratio of similar to 10(2). Using the transmission line method, the resistivity of the GaN nanowires and specific contact resistivity were estimated to be 7.8 x 10(-2) Omega cm and 1.7 x 10(-5) Omega 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.