Bilayer graphene/HgCdTe based self-powered mid-wave IR nBn photodetector

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.