NiO/GaN heterojunction diode deposited through magnetron reactive sputtering

NiO films were prepared with different O2/Ar reactive sputtering gas ratios. The morphology, crystalline structure, and optical properties of the as-deposited films are dependent on sputtering gas ratios. The NiO/GaN heterojunction diode was fabricated with NiO film obtained at medium O content (25%). Compared with the Ni/GaN Schottky diode, the NiO/GaN heterojunction diode shows a relatively higher turn-on voltage and lower reverse leakage current. The temperature-dependent current–voltage characteristics demonstrate that the thermionic emission dominated the reverse leakage current of the NiO/GaN diode.