Bilayer graphene/HgCdTe based very long infrared photodetector with superior external quantum efficiency, responsivity, and detectivity

Abstract

We present a high-performance bilayer graphene (BLG) and mercury cadmium telluride (Hg1 xCdx¼0.1867Te) heterojunction based very long wavelength infrared (VLWIR) conductive photodetector. The unique absorption properties of graphene enable a long carrier lifetime of charge carriers contributing to the carrier-multiplication due to impact ionization and, hence, large photocurrent and high quantum efficiency. The proposed p+-BLG/n-Hg0.8133Cd0.1867Te photodetector is characterized and analyzed in terms of different electrical and optical characteristic parameters using computer simulations. The obtained results are further validated by developing an analytical model based on drift-diffusion, tunneling and Chu's methods. The photodetector has demonstrated a superior performance including improved dark current density (1.75 10 14 mA cm 2 ), photocurrent density (8.33 mA cm 2 ), internal quantum efficiency (QEint 99.49%), external quantum efficiency (QEext 89%), internal photocurrent responsivity (13.26 A W 1 ), external photocurrent responsivity (9.1 A W 1 ), noise equivalent power (8.3 10 18 W), total noise current (1.06 fA), signal to noise ratio (156.18 dB), 3 dB cut-off frequency (36.16 GHz), and response time of 9.4 ps at 77 K. Furthermore, the effects of different external biasing, light power intensity, and temperature are evaluated, suggesting a high QEext of 3337.70% with a bias of 0.5 V near room temperature.