p-Type thin film field effect transistors based on lithium-doped nickel oxide channels grown by pulsed laser deposition

Staggered back-gated Field Effect Transistor (FET) structures were made by growing Li-doped NiO on S_i3N₄/SiO₂/Si (111) using room temperature pulsed laser deposition. Optical studies showed over 80% transmission for the NiO:Li channel at wavelengths > 500nm. The MISFET revealed rectifying transfer characteristics, with a V_ON close to zero, a channel mobility of ~ 1 cm²/Vs, a gate leakage current (at +5V) of 0.8 mA and an I_ON/I_OFF ratio (at a Vgs of -15V) of ~ 10³. The transistors showed enhancement-mode output characteristics indicative of a p-type channel with sharp pinchoff, hard saturation, a comparatively high (milliampere range) Id and a relatively low on-resistance of ~11 kΩ. Hence the adoption of Li doping in NiO channels would appear to be a promising approach to obtain p-type TFTs with superior transparency, speed and energy efficiency.