Polarization-sensitive photoresponse in few-layer ZrSe3 photodetectors

We present an in-depth spectral characterization of the fundamental optical and optoelectronic properties of few-layer ZrSe₃, a layered semiconductor of the group IV-V transition metal trichalcogenide family known for its in-plane anisotropic structure and quasi-1D electrical and optical characteristics. Our comprehensive analysis, conducted at both room temperature and in cryogenic vacuum, reveals that ZrSe₃ exhibits pronounced excitonic features in its optical spectra, which are highly sensitive to light polarization. These features are also evident in photocurrent spectra, presenting a strongly dichroic photoresponse with dichroic ratios exceeding 4 for excitation on resonance with the main exciton level. By comparing optical and optoelectronic spectral measurements, we elucidate the contributions of optically generated excitons to photocurrent. This work addresses substantial gaps of information in earlier literature for ZrSe₃ and advances the understanding of its unique symmetry and optical properties, paving the way for its application in nonlinear optoelectronic devices.