Growth and characterization of p-ZnO:Cu thin film and its homojunction application

Copper doped ZnO films (CZO) with p-type semiconducting behaviour and an average transparency of 50% in the visible region were deposited on glass substrates at room temperature by RF magnetron co-sputtering. The high resolution x-ray photoelectron spectrum of Cu 2p core level indicates that the Cu ions in the film are in a bivalent state of +1 and +2. Both Cu1+ and Cu2+ are found to contribute to the p-type conductivity of the film via different means. Room temperature PL measurement shows a red shift of excitonic emission and an increase in the visible emission with Cu doping. p-ZnO:Cu/i-ZnO/n-ZnO homojunction with a turn on voltage of 2.7V and an ideality factor of 8 was fabricated with the device structure Au/Ti/n-ZnO/i-ZnO/p-CZO/Au.