Investigating the Photodetectors and pH Sensors of Two-Dimensional MoS₂with Different Substrates

We successfully fabricated MoS2 photodetectors with different layers by sulfurization. It is found that the dark current increases with the number of layers. The three-layer MoS2 photodetector has the largest response, which is 3.23 × 10-6 A/W at 10 V. However, the current of the switching light was less than that of the previous cycle. It was presumed that the lifetime of the light-excited carriers was short, or more carriers would be trapped in the defects every cycle. For MoS2 EGFET pH sensors, the sensitivity and linearity results showed that FSS performed better than on Si substrate with 200 nm SiO2. From the time-dependent response measurement, it was observed that the response of the two-layer MoS2 EGFET pH sensors is very fast and stable, showing good reliability. In the future, MoS2 sensors can be combined in different fields, such as biomedical science, agriculture, and fishery, for sensing applications and real-time monitoring.