Photocurrent Spectroscopy of Titanium Trisulfide Nanoflakes

Titanium trisulfide (TiS3) is an emerging 2D semiconductor which possesses a direct bandgap in the near-infrared regime, along with strong polarization-dependent electronic and optical properties, making it a promising material for various optoelectronic applications. However, constrained by the infrared response, it is challenging to characterize the bandstructure of TiS3 via optical spectroscopy, especially for devices based on thin layer TiS3, which often exist in the form of ribbon due to their quasi-1D atomic structure. In this work, we carry out low-temperature polarization-dependent photocurrent spectroscopy characterization of TiS3 ribbons. We clearly resolve the bandgap of TiS3 for both thick and thin flakes, and the results are consistent with the theoretical expectation. Our findings are crucial to the understanding of the electronic structure of TiS3 and lay the foundation for future device applications.