We report on the fabrication of top-gate phototransistors based on a few-layered MoS
2 nanosheet with a transparent gate electrode. Our devices with triple MoS
2 layers exhibited excellent photodetection capabilities for red light, while those with single- and double-layers turned out to be quite useful for green light detection. The varied functionalities are attributed to energy gap modulation by the number of MoS
2 layers. The photoelectric probing on working transistors with the nanosheets demonstrates that single-layer MoS
2 has a significant energy bandgap of 1.8 eV, while those of double- and triple-layer MoS
2 reduce to 1.65 and 1.35 eV, respectively.
Keywords:
MoS2;
phototransistor;
photoresponse;
energy gap