Abstract:
The photoelectrical performance of a selfpowered high performance unipolar infrared (IR)
photodetector is demonstrated utilizing Silvaco TCAD
software. The unipolar IR photodetector is based on
bilayer graphene (BLG) and Hg1–xCdxTe
heterojunctions. The proposed unipolar n
+
-BLG/n–
-
Hg0.59Cd0.41Te (barrier)/n+
-Hg0.666Cd0.334Te (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/cm2
, photocurrent density of 97 pA/cm2
, photosensitivity of 2.2×106
,
the external quantum efficiency (QEext) of 53.86%,
responsivity of 1.82 A/W, specific detectivity (D*
) of
1.06×1018
cmHz1/2/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
QEext of the unipolar device is estimated to be between
93.03% and 0.03% under MWIR illumination (50
μW/cm2
). The results indicate that the BLG/Hg1–xCdxTe
based nBn photodetector has the advantages for
application in low-noise and high performance
photoelectrical devices.
