Bilayer Graphene/HgCdTe Based Self-powered Mid-wave IR nBn Photodetector

The photoelectrical performance of a self-powered high performance unipolar infrared (IR) photodetector is demonstrated utilizing Silvaco TCAD software. The unipolar IR photodetector is based on bilayer graphene (BLG) and Hg
_1-x
Cd
_x
Te heterojunctions. The proposed unipolar n
⁺
-BLG/n
^-
Hg
_0.59
Cd
_0.41
Te (barrier)/n
⁺
-Hg
_0.666
Cd
_0.334
Te (nBn) device exhibits mid-wavelength IR (MWIR: 2-5 μm) detection capabilities and excellent self-powered performance, with dark-current density of 4.3×10
^-5
pA/cm
²
, photo-current density of 97 pA/cm
²
, photosensitivity of 2.2×10
⁶
, the external quantum efficiency (QE
_ext
) of 53.86%, responsivity of 1.82 A/W, specific detectivity (D
^*
) of 1.06×10
¹⁸
cmHz
^1/2
/W and noise equivalent power (NEP) of 5.93×10
^-22
W at an ambient temperature of 77 K. The bias-dependent photoresponse is also observed at a cutoff wavelength of 4.2 μm. Under a bias of -0.5 V, the QE
_ext
of the unipolar device is estimated to be between 93.03% and 0.03% under MWIR illumination (50 μW/cm
²
). The results indicate that the BLG/Hg
_1-x
Cd
_x
Te based nBn photodetector has the advantages for application in low-noise and high performance photoelectrical devices.