Phototransistors Utilizing Individual WS2 Nanotubes

We report on the photoresponse characteristics of tungsten disulfide (WS₂) nanotubes. Field effect transistors (FETs) were fabricated by using individual WS₂ multiwall nanotubes. Photo-sensitivity to visible light is clearly observed, with enhancement of the channel conductivity, carrier mobility and carrier concentration upon illumination in the visible regime. Polarization-sensitive measurements reveal a strong anisotropy of the photocurrent on the polarization angle of the incident light with respect to the WS₂ nanotube axis. This nano-scale transistor capable of detecting visible light would have a wide range of applications in medical and consumer electronics.