p-channel NiO thin film transistors grown with high k ZrO₂ gate oxide for low voltage operation

A low voltage operative and optically transparent p- type Nickel oxide thin film transistor (TFT) was realized. We have systematically investigated the structural and transport properties of both NiO and ZrO₂ thin films grown by dc magnetron sputtering. It is shown that a 30 nm thickness of ZrO₂ thin film act as gate oxide dielectric for the TFTs. The Metal-Insulator-Metal (MIM) study revealed a high dielectric constant (k) of 28 and the leakage current density significantly persisted at ∼1 nA cm⁻² at an applied field of 7 MV cm⁻¹. Further, active layer of p-NiO film was deposited on ZrO₂ gate oxide dielectric film and were processed at different post annealing temperatures. The TFTs electrical characteristics with the staggered bottom gate configuration of ITO/ZrO₂/NiO/Ag exhibits a stable 10⁴ of I_on/I_off ratio with a field effect mobility of 15.8 cm²V⁻¹s⁻¹ and recorded sub-threshold swing slope of 512 mV/dec. Moreover, the trap density of 1.82 × 10¹² cm⁻³ was estimated from the Levinson’s plot. Overall, the post annealing temperature seems to improve the transport characteristics of the fabricated TFTs.