Experimental comparison between photoconductive and graphene-based photogating detection in a UV-A region

Abstract

Photoconductive detectors that use intrinsic absorbent materials include a wide range of detectors. In this paper, a photoconductive detector is fabricated using a titanium dioxide (TiO2) thin film. The mechanism of the photodetector is changed to the photogating mechanism by transferring monolayer graphene onto the TiO2 thin film, which shows a great responsivity with a slight change in the fabrication process. Since the maximum responsivity can be obtained by applying and adjusting the gate voltage, the gate voltage is set in all experiments, and the effect of the gate voltage is investigated in both detectors. It is observed that by increasing the gate voltage, the responsivity of the photogating detector increases to 40 A/W at a gate voltage of 15 V. However, in the photoconductive detector, the increase in the gate voltage does not have a particular effect on the detector responsivity. In the photogating detector, the increase in the responsivity due to the increase in the gate voltage is attributed to applying the gate voltage to the graphene layer and not the absorber layer. The efficiency of both detectors is confirmed up to a frequency of 5 kHz.