A novel NiO-based p-i-n ultraviolet photodiode

In this study, the electrical and optical properties of a novel NiO-based homojunction p-i-n photodiode are reported. The p-i-n diode structure consists of Mg-doped, intrinsic and Cu-doped NiO from the top to the bottom layers, respectively. The photodiode structure was grown on a 0.7 % Nb-doped SrTiO3 (001) substrate using molecular beam epitaxy. The homojunction p-type NiO:Mg/i-NiO/n-type NiO:Cu exhibits diode characteristics. The ideality factor and barrier height of the diode are found to be 1.26 and 0.66 eV, respectively. The photoconductive properties of the photodiode were investigated by operating the diode under reverse bias, and spectral excitation of a Xe lamp. The responsivity of the photodiode is determined to be 295 mA/W at 3.9 eV. A constant photoresponse of the p-i-n photodiode between 3.75 eV and 6 eV with a responsivity of 250 mA/W is observed.