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 × 10−3Ω-cm and majority carrier (electrons) concentration of about 3.90 × 1020cm−3. Film annealed at 473 K was p-type having resistivity of 1.54 × 10−1Ω-cm and majority carrier (hole) concentration of about 4.45 × 1018cm−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.