Ultrahigh-Sensitivity and Fast-Speed Ultraviolet Pulsed Photodetectors Based on the Transverse Thermoelectric Effect of Inclined PbBi2Te4 Thin Films

The transverse thermoelectric (TTE) effect of inclined thin films, originating from the anisotropy of the Seebeck coefficient of the films, has received extensive attention owing to its great application potential in self-powered photodetectors and heat flux sensors. In this paper, a novel TTE ultraviolet pulsed photodetector was constructed by using a high-quality c-axis inclined PbBi2Te4 thin film prepared on an SrTiO3 substrate via a pulsed laser deposition technique. The device exhibited very high voltage sensitivity Rs as well as ultrafast response time, with an Rs of about 25.75 V/mJ and rise time of about 18 ns. In addition, the device showed long-term working stability in air after coating a thin layer of Al2O3 and perfect linearity with an R-squared coefficient close to 1. The results demonstrate that PbBi2Te4, a compound with large anisotropy of the Seebeck coefficient, is a new promising material for fabricating high-performance TTE-based ultraviolet pulsed photodetectors.