Effective Self-Powered Semimetal TaTe2 Photodetector with the Thermal Localization Photothermoelectric Effect from Ultraviolet to Mid-Infrared Range

Ultra-broadband photodetectors based on semimetal crystals have recently become popular because of their gapless band structures. In particular, semimetal crystals have large carrier mobility or high Seebeck coefficient; this almost eliminates the possibility of using semimetal crystals as photodetectors. In addition, a larger temperature gradient can cause photocurrent generation based on the photothermoelectric effect. Surprisingly, the TaTe2 crystal has a huge absorption coefficient (approximate to 10(4) cm(-1)), a minimal specific heat (approximate to 0.172 J g(-1) K-1), and a low thermal conductivity (0.3 W m(-1) K-1), which is beneficial for generating a high photothermal conversion efficiency of 30.2%, despite its small Seebeck coefficient, and achieving a large temperature gradient occurs for the heat generated by external illumination. Herein, the possibility of photoresponse based on the TaTe2 detector is explored, which has a low carrier mobility (approximate to 10 cm(2) V-1 s(-1)) and a small Seebeck coefficient (approximate to 7.1 mu V K-1). The self-powered TaTe2 photodetector can also provide a competitive photoresponse range from 355 to 2715 nm and exhibit a maximum responsivity of 1.1 mA W-1 with a detectivity of 4.7 x 10(8) Jones at 455 nm. This study provides a new design scheme and operating mechanism for semimetal photodetectors and enriches semimetal crystal photodetectors.