Near-infrared photodetector based on MoS2 QDs/GaAs heterojunction with an Al2O3 interface passivation layer

Abstract

Two-dimensional (2D) materials have attracted many attentions since they have been discovered. In recent years, various photodetectors made of 2D materials have been continuously reported. In this study, a near-infrared photodetector is fabricated by consisting of a heterojunction of MoS2 quantum dots (QDs) and p-type GaAs substrate. In the subsequent test, it is found that the device has response to three wavelengths of 808 nm, 1064 nm, and 1310 nm, where the 1064 nm band response is the highest. Further test and comparison also find that the insertion of Al2O3 passivation layer with 2 nm thickness at the interface between MoS2 QDs and GaAs and thermal annealing of MoS2 QDs can improve the performance of the device. Finally, under the bias condition of −0.1 V, the response can reach 143.2 mA⋅W−1, and the detection rate is 3.32 × 1010 cm⋅Hz1/2⋅W−1. Under the signal frequency of 2 kHz, the rise time and fall time of the device are 12 μs and 32 μs, respectively; at 4 kHz, the low response time of 24 μs and 74 μs can be achieved, respectively.