One-dimensional analysis of N-on-p Pb1−xSnxSe compositionally graded heterojunction photodetectors

This work presents a theoretical investigation of the performance of N-on-p Pb1−xSnxSe heterojunction photodiodes with a linear gradient in composition. We quantify the improvement of the quantum efficiency, R0A product, and detectivity for a graded heterojunction device as compared to a basic p-n homojunction photodetector. In addition to enhanced overall device performance, the graded heterojunction diode exhibits considerable improvements when surface recombination velocities are taken into account. For low surface recombination velocities the detectivity of the graded N-on-p heterostructure increases nearly two-fold in comparison to the p-n homojunction, while for high surface recombination velocities the detectivity of the graded heterostructure increases by as much as an order of magnitude.