A highly efficient bilayer graphene-HgCdTe heterojunction based p + -n photodetector for long wavelength infrared (LWIR)

Abstract

In this paper, p +–bilayer graphene (BLG)/nHg0.7783Cd0.2217Te heterojunction based long wavelength infrared (LWIR: 2-12 µm) photodetector is reported. The LWIR radiations are absorbed in lightly doped nHg0.7783Cd0.2217Te active layer. The drift-diffusion approach is used for the simulation of the device. Different recombination mechanism models such as Shockley-Read-Hall, Auger, and optical are considered for computing dark current. The photodetector exhibits dark current of 3.5 pA, photocurrent of 1.9 nA, and Iph/Idark ratio of 543 at –1 V bias. The maximum external quantum efficiency (QEext) of 88.38%, photocurrent responsivity of 4.5 AW–1 , specific detectivity (D* ) of 1.8×1015 cmHz1/2W–1 , noise equivalent power (NEP) of 3.53×10–19 W, and the 3-dB bandwidth of about 64.8 GHz at –0.5 V is achieved at 77 K, confirms the suitability of proposed photodetector for low noise applications.