GaN-Based Very Narrow Band-Pass p-i-n Ultraviolet A Photodetectors

The modeling of aluminum gallium nitride (AlGaN) p-i-n photodetectors response in the very narrow ultraviolet A (UV-A) range is reported in this paper. To obtain narrow-band response and high short wave rejection ratio, two AlGaN buffer layer with Al-content higher than that of the absorption region were designed between the substrate and un-doped AlGaN absorption layer to act under backside illumination as filter for short wavelength radiation. The band-pass of these a structure depends on the buffer layer Al-content. Electronic-band-structure calculations show that the blocking layer is the crucial parameter to achieve both a high short wave rejection ratio and a low dark current.