High Performance Broadband Polarization-Sensitive Photodetector Enabled by Mixed-Dimensional n-ReS2/p-GaAs van der Waals Heterostructure.

The realization of photodetectors capable of broadband detection, self-powered operation, and polarization sensitivity is crucial for advancing next-generation optoelectronic technologies. A mixed-dimensional van der Waals heterojunction photodetector composed of two-dimensional ReS2 and three-dimensional p-type GaAs was designed and fabricated in this study. The device effectively achieves broadband self-powered photodetection across the spectral range of 254-808 nm at zero external bias. When exposed to 365 nm ultraviolet radiation, the photodetector delivers a high responsivity of 0.15 A/W and a specific detectivity reaching 8.39 × 1011 Jones. Additionally, it demonstrates rapid temporal response, with rise and decay times of 77 and 81 ms, respectively. Benefiting from the intrinsic in-plane anisotropy of the ReS2 crystal lattice and the effective depletion region at the ReS2/GaAs interface, the device reveals pronounced polarization sensitivity, with the polarization ratios of 2.11 at Vds = 0 V and 14.46 at Vds = -1 V under 405 nm. These findings underscore the promising prospects of n-ReS2/p-GaAs heterostructures in enabling multifunctional, energy-efficient, and high-performance photodetection, with particular relevance to polarization-resolved imaging and next-generation optical sensing technologies.