Photon-Recycling In Ultraviolet Gan-Based Photodiodes With Porous Algan Distributed Bragg Reflectors

GaN-based ultraviolet photodiode with porous distributed Bragg reflectors (DBR) structure was demonstrated. The n(+)-AlGaN:Si epitaxial layers with high refractive index had been etched as porous-AlGaN layers with low refractive index through an electrochemical etched process. The peak wavelength of the responsivity spectra was measured at 355 nm, which was matched to the high reflectance wavelength region of the porous reflector. High photocurrent and large UV/visible rejection ratio were measured in the GaN photodiode with the porous-AlGaN reflector due to the light recycling process in the resonance cavity structure.