p-Type transparent thin films of CuY1−xCaxO2

Thin films of CuY1−xCaxO2 that are p-type conductors have been prepared by thermal co-evaporation. The films are polycrystalline on amorphous substrates and c-axis oriented on crystalline substrates. Calcium doping was necessary to produce conductive films, and the highest conductivity recorded was 1.0 S cm−1. The average transparency in the visible region is approximately 40–50%, for conducting films approximately 250 nm thick, and in the infrared approximately 70% for a 350-nm conducting film. The optical spectra give evidence for a bandgap of 3.5 eV. We have demonstrated an all-oxide p–n diode using CuY1–xCaxO2/Zn1–xAlxO.