A study of transparent P-type semiconducting oxide Cu-Al-O

Abstract

The bulk CuAlO2 powder and targets for physical vapour depositions were successfully fabricated. CuAlO2 phase was achieved at 1200A?C after calcination for more than 10 hours. The bulk CuAlO2 shows p-type conductivity and has an average resistivity of ~114 i??-cm. Cu-Al-O thin films were deposited by pulsed laser deposition (PLD) and radio-frequency (RF) magnetron sputtering. Reactive sputtering of metallic Cu and Al targets were also investigated in the environment of Ar/O2. Cu/Al atomic ratio close to 1-to-1 was achieved. The films prepared by PLD and sputtering of single-oxide target showed poor conductivities whereas films prepared by reactive co-sputtering showed moderate conductivity. Post-deposition annealing (PDA) was performed to improve the electrical properties of the as-deposited films. The films still possessed multiple phases after annealed at 750A?C. Formation of nearly-pure CuAlO2 thin films was achieved after annealing at 1000A?C for 3 hours with Ar flow and the electrical conductivity improved significantly.