Precisely controllable n-type doping in MoTe2 field effect transistors by hydrazine treatment

An accurate and controllable n-type doping method for MoTe2 field effect transistors is developed by hydrazine treatment. It is shown that hydrazine molecules are absorbed physically without a new substance being formed, as determined by X-ray photoelectron spectroscopy measurements. The conduction type, electron concentrations, and minimum conductivity points in the transfer characteristics could be modulated precisely for a wide range by varying the concentration of hydrazine solution. Compared to pristine MoTe2 control devices, the electron concentrations are changed from 9.67 x 10(11) cm(-2) to 3.46 x 10(12) cm(-2) in the n-type regime, while the electron current on/off ratio is increased from 10 4 to 10 6 after 5 wt. % of hydrazine treatment. It is also interesting to observe that the ambipolar window increases almost linearly as the device temperature is reduced from 260K to 5K. The effective Schottky barrier heights for electrons in hydrazine treated MoTe2 field-effect transistors are extracted and found to be lower than 0.024 eV, indicating that the thermionic emission is not dominated. Furthermore, a lateral MoTe2 p-n junction with a rectification ratio higher than 10 3 and an ideality factor of around 1.66 is demonstrated through selective doping. This developed unique method of n-type doping and p-n junction creates an opportunity to fabricate high performance functional devices based on 2D layered materials. Published by AIP Publishing.