n-ZnO/p-GaN/α-Al2O3 heterojunction as a promising blue light emitting system

It is reported on the fabrication and characterization of light emitting n-ZnO/p-GaN heterojunction. Firstly, a Mg-doped p-GaN layer was grown on (0001) sapphire substrate by the molecular-beam epitaxy technique, then thin Ga-doped n-ZnO film was deposited by the chemical vapor deposition in the low-pressure system. Diode-like rectifying behavior of this heterojunction and room temperature electroluminescence in the blue-violet region with peak wavelength 430 nm under forward bias were observed. Light-current characteristics of this structure feature a superlinear behavior in the low current range with a slope 1.9 and a sublinear behavior with a slope 0.85 in the high current range.