Visible-Blind APD Heterostructure Design With Superior Field Confinement and Low Operating Voltage

We report on the polarization engineering of GaN/AlGaN heterostructures for the improvement of III-Nitride photodetectors through physics-based device simulations. Various heterojunction p-i-n and p-i-n-i-n designs are proposed and analyzed in this context. Our analysis shows that the introduction of a higher-bandgap AlGaN layer and n-type doped composition graded interlayers reduce operating voltage of an avalanche photodetector (APD) by almost 40% while enabling backside illumination geometry that is critical for the realization of detector arrays. The results of the simulation studies predict an APD device design that is less susceptible to premature breakdown outside of the multiplication region due to superior electric field confinement.