Modeling and simulation of HgCdTe based p +–n–n + LWIR photodetector

Abstract

In the present paper the performance of p +–n–n + Hg 1− x Cd x Te long wavelength infrared (LWIR) homojunction photodetector ( x ≈ 0.22) has been analyzed theoretically and simulated numerically using ATLAS software from SILVACO®. The results obtained in the two cases are compared and contrasted with the available experimental results. The energy band diagram, electric field profile, carrier concentration, dark current, dynamic resistance, quantum efficiency and detectivity have been calculated and optimized as a function of different variables such as device thickness, reverse voltage and operating wavelength in order to optimize the performance of p +–n–n + photodetector at 77 K. The dependence of the p +–n junction position within homostructure on bandgap energy profiles and the influence of doping concentration on photodetector parameters have been studied. In the present model the Johnson–Nyquist and shot noise have been considered in calculation of detectivity. Results of our study reveal that under suitable biasing conditions the photodetector exhibits a dark current, I D ≈ 10 −7 A, and a zero bias resistance, R 0 = 10 6 Ω and a detectivity 8 × 10 9 mHz 1/2/W.