2. Experimental details
Solid-state reaction between stoichiometric mixture of Cu2O and Al2O3 at 1400 K in air produced CuAlO2 powder.This powder was then placed into a grooved aluminium holder (~5 cm diameter) and pressed into pellet by hydrostatic pressure and used as target for dc sputtering. The
sputtering unit was evacuated by standard rotary-diffusion pump arrangement to a base pressure of 104 Pa. The target was arranged as an upper electrode and -ve bias was applied on it.Ultrasonically cleaned glass and Si substrates were placed on the lower electrode and connected to the ground of the power supply. The electrode distance was taken as 1.8 cm. Ar and O2 (40 vol.%) were taken as sputtering gas and the sputtering was done in an elevated substrate temperature(~453 K) to achieve high crystallinity in the film.Postdeposition annealing of the films (at 473 K) in an O2 atmosphere (20 Pa pressure) for different annealing times(ta) ranging from 30 to 150 min were performed to induce