P-type semiconducting Cu₂O–NiO thin films prepared by magnetron sputtering

P-type semiconducting thin films consisting of a new multicomponent oxide composed of Cu₂O and NiO were deposited on glass substrates by r.f. magnetron sputtering using Cu₂O–NiO mixed powder targets. The multicomponent oxide thin films deposited in an Ar atmosphere with a Ni content (Ni/(Cu + Ni) atomic ratio) in the range from 0 to 100 at.% were found to be p-type semiconductors. As the Ni content was increased in the range from 0 to about 30 at.%, the energy bandgap of the resulting films gradually increased as well as the obtained resistivity increased from 70 to 4 × 10⁴ Ω cm, a consequence of decreases in both the Hall mobility and the hole concentration. The films prepared with a Ni content of about 30–50 at.% exhibited a relatively constant resistivity and energy bandgap. The resistivity and the energy bandgap of films prepared with a Ni content above about 60 at.% considerably increased as the Ni content was increased. Furthermore, a pn thin-film heterojunction prepared by depositing undoped n-ZnO and p-multicomponent oxide (Ni content of 50 at.%) thin films exhibited a rectifying I–V characteristic.