Interface engineering by inserting Al2O3 tunneling layer to enhance the performance of graphene/GaAs heterojunction photodetector

Interface engineering is an effective way to improve the performance of graphene-based photodetectors. Here, a graphene/GaAs heterojunction photodetector is fabricated, and when inserting an Al2O3 tunneling layer, its performance is improved through direct tunneling (DT) and Fowler-Nordheim tunneling (FNT). According to the experimental results, it is found that the thickness of the tunneling layer has a great influence on the performance of the photodetector. Compared with graphene/GaAs photodetector, the performance of graphene/Al2O3(2 nm)/ GaAs photodetector is significantly improved with the responsivity, detectivity, and external quantum efficiency value of 0.80 A/W, 3.02 x 1011 Jones and 306% under 1 mW/cm2 light intensity at 2 V bias. Meanwhile, fast response is also observed (rise/decay time of 3 ms/8.6 ms). The improvement of the photodetector's performance in this work is mainly attributed to the effective modification of the interface state by the Al2O3 tunneling layer and the effect of the two tunneling mechanisms based on DT and FNT.