A Highly Efficient Bilayer Graphene-HgCdTe Heterojunction Based $p^{+}-n$ Photodetector for Long Wavelength Infrared (LWIR)

In this paper, $p^{+}$ =bllayer graphene (BLG)/n@ $\mathbf{Hg}_{0.7783}\mathbf{Cdo}_{0.2217}$ Te heterojunction based long wavelength infrared (LWIR: 2–12 J.1m) photodetector is reported. The LWIR radiations are absorbed in lightly doped n- $\text{Hg}_{0.7783}\text{Cd}_{0.2217}$ Te 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 $I_{ph}/I_{dark}$ ratio of 543 at −1 V bias. The maximum external quantum efficiency $(QE_{ext})$ of 88.38%, photocurrent responsivity of 4.5 $\text{AW}^{-1}$, specific detectivity (D*) of $1.8\times 10^{15}\text{cmHz}^{1/2}\mathrm{W}^{-1}$, noise equivalent power (NEP) of $3.53\times 10^{-19}\ \mathrm{W}$, 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.