Bilayer graphene/HgCdTe based very long infrared photodetector with superior external quantum efficiency, responsivity, and detectivity

Abstract

We present a high-performance bilayer graphene (BLG) and mercury cadmium telluride (Hg1−xCdx=0.1867Te) heterojunction based very long wavelength infrared (VLWIR) conductive photodetector.

Enhanced Photoelectric Properties of Multilayer Graphene Mg2Si/Si Heterojunction Photodetector

“…Such an EQE value which is greater than 100% is achieved in cases for more than 5 Graphene layers. This is attributed to the carrier multiplication effect in Graphene [16].…”

“…However, due to their zero energy bandgap and small optical absorption (about 2.3%), monolayer Graphene PD has a high dark current density and low photocurrent response (< 1 mA/W) at room temperature. These constrain their practical applications in optical communication systems [14][15][16]. Dark current density can be reduced by chemically doped bandgap engineering, or by using two or more Graphene layers [16,17].…”

“…These constrain their practical applications in optical communication systems [14][15][16]. Dark current density can be reduced by chemically doped bandgap engineering, or by using two or more Graphene layers [16,17]. In addition, it has been shown that by p-type doping in the Graphene layers the Fermi level of Graphene can be moved near the valence band [18] thus the barrier height is increased.…”

“…This produces a wide range of effects on the depletion region and the high built-in electric field at the interface. This high electric field also leads to effective carrier separation, drift, and highly efficient devices [16,17,19].…”

Influence of multilayer graphene doping concentrations on detection properties of MLG/Mg2Si/Si heterojunction photodetector

“…Peak EQE appears to diminish as the peak PD responsivity appears to decrease. Such a high value of EQE greater than 100% is due to the carrier multiplication effect in MLG [13,16]. One valence band electron in MLG's conduction band is excited to a higher energy state by the incident infrared energy, which further excites another valence band electron to the conduction band.…”