Electrical transport of bottom-up grown single-crystal Si _1-xGe_x nanowire

In this work, we fabricated an Si_1-xGe_x nanowire (NW) metal-oxide-semiconductor field-effect transistor (MOSFET) by using bottom-up grown single-crystal Si_1-xGe_x NWs integrated with HfO ₂ gate dielectric, TaN/Ta gate electrode and Pd Schottky source/drain electrodes, and investigated the electrical transport properties of Si _1-xGe_x NWs. It is found that both undoped and phosphorus-doped Si_1-xGe_x NW MOSFETs exhibit p-MOS operation while enhanced performance of higher I_on∼100 nA and I_on/I_off∼10⁵ are achieved from phosphorus-doped Si_1-xGe_x NWs, which can be attributed to the reduction of the effective Schottky barrier height (SBH). Further improvement in gate control with a subthreshold slope of 142 mV dec^-1 was obtained by reducing HfO₂ gate dielectric thickness. A comprehensive study on SBH between the Si_1-xGe_x NW channel and Pd source/drain shows that a doped Si_1-xGe_x NW has a lower effective SBH due to a thinner depletion width at the junction and the gate oxide thickness has negligible effect on effective SBH.