Tuning electrical properties of transparent p-NiO/n-MgZnO heterojunctions with band gap engineering of MgZnO

Transparent p-n heterojunctions composed of p-type NiO and n-type MgZnO thin films were fabricated on indium-tin-oxide-coated glass substrates by sol-gel spin coating technique. The p-n junctions exhibit typical current-voltage behaviors with good rectifying characteristics, and their electrical properties can be effectively tuned by band gap engineering of n-MgZnO. With increment of Mg content in n-MgZnO layer, enlarging band gap can lead to the higher forward threshold voltage, higher breakdown voltage, and lower reverse saturation current. The electrical behaviors of the p-n junctions can be further improved by using compositionally graded n-MgZnO layer instead of single n-MgZnO layer. These results suggest that the transparent all-oxide p-NiO/n-MgZnO heterojunctions can find applications in transparent electronic devices.