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.
