Fabrication of246 nm back-illuminated AlGaN solar-blind ultraviolet p-i-n photodetector

A short wavelength back-illuminated AlGaN solar-blind ultraviolet p-i-n photodetector was designed and fabricated. It was photosensitive in the waveband225-255 nm, and the peak wavelength was246 nm. A back-illuminated p-i-n heterojunction structure was grown on transparent sapphire substrate using MOCVD, the AlxGa1-xN alloy composition of the n-type window layer was71%, and the alloy composition of the unintentionally doped(UID) absorber layer was52%. The dark current measured at zero bias was27 pA, and the photocurrent was2.7 nA, while the peak responsivity was23 mA/W. A128×128 pixels solar blind ultraviolet photodetector array was fabricated on this basis. The diameter of each pixel was44μm with a50μm pitch