Multilayer WS for low-power visible and near-infrared phototransistors.

Mechanically exfoliated multilayer WS flakes are used as the channel of field effect transistors for low-power photodetection in the visible and near-infrared (NIR) spectral range. The electrical characterization as a function of the temperature reveals devices with n-type conduction and slightly different Schottky barriers at the drain and source contacts. The WS phototransistors can be operated in self-powered mode, yielding both a current and a voltage when exposed to light.