High‐Gain Phototransistors Based on a CVD MoS2 Monolayer

A phototransistor based on a chemical vapor deposited (CVD) MoS2 monolayer exhibits a high photoresponsivity (2200 A W−1) and an excellent photogain (5000). The presence of shallow traps contributes to the persistent photoconductivity. Ambient adsorbates act as p-dopants to MoS2, decreasing the carrier mobility, photoresponsivity, and photogain.