Abstract:
We present novel p+-bilayer graphene (BLG) and
mercury cadmium telluride (MCT)-based single- and dualjunction photodetectors, namely, p+-BLG/n–-MCT and p+-
BLG/n–-MCT/n+-MCT, operating in long infrared regime. The
optoelectronic characterizations utilizing Silvaco Atlas TCAD are
validated by analytical modeling. All the devices demonstrate
self-powered mode operation and exhibit more than 106 times
enhancement in photocurrent density. The dual-heterojunction
photodetector demonstrates rapid photocurrent switching with the
rise and fall time of ∼0.05 and ∼0.013 ps, respectively, than that
of single-heterojunction-based photodetectors. The highest external quantum efficiency (QEext), external photocurrent responsivity, and lowest noise equivalent power of 85.8%, 7.33 A/W, and
4.72 × 10−20 W, respectively, are found for the dual-heterojunction
photodetector with a wavelength of 10.6 µm at 77 K. Such optimum photodetection performance is attributed to the presence
of a huge amount of electric field (180 kV/cm) at n–-n+ heterojunction, which accelerates the photogenerated electrons resulting in effective photocurrent. It is further demonstrated that the
temperature-dependent QEext with values >100% is due to the
carrier multiplication effect in BLG.
