Study on AlGaN P-I-N-I-N solar-blind avalanche photodiodes with Al0.45Ga0.55N multiplication layer

Abstract

This paper presents the design for a heterojunction AlGaN solar-blind avalanche photodiode (APD) with improved noise performance. Increasing the Al composition of AlGaN in the multiplication layer from 0.40 to 0.45 was calculated to significantly reduce the excess noise factor of this heterojunction APD. The polarization electric field induced in the multiplication layer had the same direction as the applied reverse bias field, which helped lower the avalanche breakdown voltage. The calculated results demonstrated that the apparent spike in the electric field intensity at the i-Al0.4Ga0.6N/n-Al0.5Ga0.5N interface can be effectively suppressed by inserting a grading n-AlGaN layer, which helps reduce the dark current.