High sensitivity and fast response self-powered PbSe ultraviolet pulsed photodetectors based on the transverse thermoelectric effect

Abstract

Light-induced transverse thermoelectric (TTE) effect has attracted extensive attentions because of the great potential application in self-powered photodetectors. In this paper, we report the ultraviolet pulsed light-induced TTE effect in the inclined PbSe thin films. Without any external voltage applied, gigantic open-circuit voltage signals with ultrafast responses in the order of nanoseconds were obtained when the film surface was irradiated by a 308 nm pulsed laser. The voltage sensitivity Rs can reach up to ∼7.75 V/mJ and the figure of merit Fm is as high as ∼350 mV/ns, both of which are higher than the best values reported in most of complex oxide thin films. In addition, the experimental results reveal that the polarity of the induced voltage will immediately reverse when the film is irradiated from the substrate side and the amplitudes of the voltage are linearly proportional to sin2α (α is the inclination angle of the films). Here, the anisotropy of the Seebeck coefficient is used to explain the origin of the TTE voltage. The results demonstrate the great potential application of PbSe thin film for the high sensitivity and fast response self-powered ultraviolet pulsed photodetectors.