Fabrication of a transparent p-n heterojunction thin film diode composed of p-CuAlO2/n-ZnO

An all-oxide transparent p-n heterojunction on a glass substrate was fabricated. The structure of the diode was ITO electrode/p-CuAlO2/n-ZnO/In electrode on the glass substrate. The p-CuAlO2 thin film was deposited by e-beam evaporation, which was annealed by the wet-oxidation method. The p-n heterojunction thin film diode showed rectifying current-voltage characteristics, dominated in forward bias by the flow of space-charge-limited current. The ratio of forward current to the reverse current exceeded 40 within the range of applied voltages of -4.0 to +4.0 V and the turn-on voltage was 0.3 V. Optical transmission of the diode was about 40% in the visible range.