Effective threshold voltage control in GaN nanowire field-effect transistors with a dual-gate structure

To control the gate threshold voltages of nano-devices, we fabricated a GaN nanowire field-effect transistor with a sandwich-type dual-gate structure in which the top- and the bottom-gate electrodes could independently apply a gate voltage bias to the nanowire conducting channel. The fabricated device showed a clear n-type gate response. The gate threshold voltage of the nanowire field-effect transistor could be effectively tuned over a wide range, from -13 V to +1 V, by scanning the topor the bottom-gate voltages between -10 and +10 V, respectively. As the top-gate voltage was varied from -10 V to +10 V, the carrier mobility increased from 16 to 56 cm²/Vs, and the channel conductance increased. The turn-on position of the channel conductance could be tuned precisely by varying the voltage at one of the gates.