Electrical transport of bottom-up grown single-crystal Si1−xGex nanowire

In this work, we fabricated an Si1−xGex nanowire (NW) metal-oxide-semiconductor field-effect transistor (MOSFET) by using bottom-up grown single-crystal Si1−xGex NWs integrated with HfO2 gate dielectric, TaN/Ta gate electrode and Pd Schottky source/drain electrodes, and investigated the electrical transport properties of Si1−xGex NWs. It is found that both undoped and phosphorus-doped Si1−xGex NW MOSFETs exhibit p-MOS operation while enhanced performance of higher Ion~100 nA and Ion/Ioff~105 are achieved from phosphorus-doped Si1−xGex 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 Si1−xGex NW channel and Pd source/drain shows that a doped Si1−xGex 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.