PtTe 2 photodetectors with negative photoconductivity under different wavelength laser irradiation

Platinum telluride (PtTe 2 ), as a newly emerged type II Dirac semimetal, has attracted much attention. Due to its excellent linear dispersive band structure and ultra -high carrier mobility, PtTe 2 show great potential in the new quantum phenomena, topological phase transitions, unconventional superconductivity and other photodetecting fields. In this paper, we report the negative photoelectric effect of photodetectors based on the type II Dirac semimetal PtTe 2 film under the laser irradiation of 405 nm, 532 nm and 808 nm. Under the condition of applying 1 V voltage, the R of the PtTe 2 device under 405 nm laser irradiation was 20 A/W and the D* was 6.9 x10 9 Jones; the R of the PtTe 2 device under 532 nm laser irradiation was 1.3 A/W and the D* was 4.1 x10 8 Jones; the R of the PtTe 2 device under 808 nm laser irradiation was 0.6 A/W and the D* was 2.1 x10 8 Jones. Under normal atmospheric pressure and room temperature conditions, we observed a negative photoconductivity phenomenon for the PtTe 2 device, where the change in photoconductivity is attributed to the light -induced desorption of O or H 2 O molecules from the surface of the material. In addition, a single -site scanning imaging system based on a PtTe 2 photodetector was designed to test the detection capability of the device. The analysis of the photocurrent effect produced by the PtTe 2 device further deepens the understanding of the photoconductivity mechanism in the field of photodetection.