High Current Density and Low Contact Resistance P-type MoTe₂ Thin Flake FETs Enabled by Oxygen Plasma Doping

Few-layer molybdenum ditelluride (MoTe₂) with a small band gap (~1.0 eV) is found promising for realizing tunnel field effect transistors (TFETs). However, the existence of a large contact resistance at the interface between metal and 2D MoTe₂ has drastically restrains the current density, which hinders its application to high performance electronics and optoelectronics. In this work, we demonstrated a controllable mild oxygen plasma doping method for achieving ultra-high hole density in thin MoTe₂ FET. By increasing the plasma treatment duration, degenerate p-type MoTe₂ FETs with enhanced hole density were obtained from the pristine n-dominated MoTe₂ FETs, achieving low contact resistance of 0.6 kΩ●µm. In order to preserve good on-off ratio and carrier mobility of the device, we exposed the contact area to oxygen plasma. Non-degenerate p-type MoTe₂ FETs with comparable on-state hole transport to the pristine electron transport were achieved without hole mobility degradation.