Electrical properties and stability of p-type ZnO film enhanced by alloying with S and heavy doping of Cu

Abstract

Single wurtzite p-type Zn1−yCuyO1−xSx alloy films with 0.081≤x≤0.186 and 0.09≤y≤0.159 were grown on quartz reproducibly by magnetron sputtering. The alloys show very stable p-type conductivity with a hole concentration of 4.31–5.78×1019 cm−3, a resistivity of 0.29–0.34 Ω cm and a mobility of 0.32–0.49 cm2 V−1 s−1. The p-type conductivity is attributed to substitution of Cu+1 for the Zn site, and the ionization energy of the Cu+1 acceptor is measured to be 53 meV, much less than that of Cu-doped ZnO reported previously. The small ionization energy is due to Cu heavy doping and increase in valence band maximum of ZnO induced by alloying with S.