Electronic transport and optoelectronic applications of a new layered semiconductor CuTaS3

Two-dimensional layered bi-transition metal chalcogenides with exotic physical and optoelectronic properties are becoming attractive and promising candidates for next-generation electronics and optoelectronics. Herein, we report a representative of bi-transition metal sulfide, the strip-shaped CuTaS3 crystal, analyzing its intrinsic electrical transport properties and potential optoelectronic applications by fabricating CuTaS3-based devices. The time-resolved Terahertz (THz) spectroscopy (TRTS) results indicate a rapid quenching of photoconductivity in CuTaS3 bulk within 4.1 ps photoexcitation. PL measurement and CuTaS3-based field effect transistors (FETs) show a typical n-type semiconducting behavior with a small, direct bandgap of 1.24 eV. Density functional theory (DFT) calculations reveal charge transfers between different atoms and phonon dispersion relations to help understand the structural and vibrational properties of CuTaS3. A CuTaS3-based-phototransistor was demonstrated with a responsivity of 7.6 mA W-1 and fast photoresponse time of 0.3-0.4 s, as well as excellent photoswitching stability. Our results may pave the way for developing other layered bi-transition metal chalcogenides and implementations in electronic and optoelectronic applications.