Postdeposition annealing of NiOx thin films: A transition from n-type to p-type conductivity for short wave length optoelectronic devices

The present work highlights the effect of postdeposition annealing (373-773 K) on the tunability of electrical conductivity of radio frequency sputtered NiOx thin films with both n-type and p-type behavior. The NiOx thin films were polycrystalline with preferred (200) orientation with high optical transmission. The as-grown NiOx thin film exhibits an n-type behavior with room temperature resistivity of 4.80 x 10(-3) Omega-cm and majority carrier (electrons) concentration of about 3.90 x 10(20) cm(-3). Film annealed at 473 K was p-type having resistivity of 1.54 x 10(-1) Omega-cm and majority carrier (hole) concentration of about 4.45 x 10(18) cm(-3). Hall effect and thermoelectric power measurements confirm a transition in electrical conduction from n-type to p-type with postdeposition annealing at 473 K. The observed tunability of electrical conductivity of NiOx thin film will pave way toward realization of p-n homojunction for short wave length optoelectronic device applications.