Near room-temperature chemical vapor deposition of 2D SbI3 on van der Waals substrates for photodetector applications

Abstract

Two-dimensional (2D) antimony triiodide (SbI₃), a layered metal halide with high intrinsic carrier mobility and anisotropic optical properties, holds significant promise for optoelectronic applications. However, the vapor-phase growth of 2D SbI₃ thin crystals has remained a significant challenge due to its low melting point (170 °C), which prevents the use of the high substrate temperatures typically needed for efficient nucleation and growth. Here, we report the chemical vapor deposition (CVD) growth of 2D SbI₃ crystals at near-room temperature (65 °C) using atomically flat van der Waals (vdW) substrates. Comprehensive characterization via Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirms the structural and chemical composition of the synthesized SbI₃. Additionally, by employing a two-step CVD strategy, we successfully fabricate SbI₃/WS₂ vdW heterostructures. Photoluminescence investigations reveal a pronounced interfacial charge transfer between SbI₃ and WS₂. Leveraging this efficient charge dynamics, we utilize SbI₃ thin crystals as photosensitizers to significantly enhance the photoresponse of WS₂-based photodetectors. Compared to pristine WS₂ devices, the SbI₃-modified WS₂ photodetector exhibits a notable enhancement in photocurrent by two orders of magnitude, achieving a responsivity of 15.8 mA W⁻¹. This work not only addresses the long-standing challenge of CVD growth of 2D SbI₃ but also establishes a platform for exploring interfacial physics and advancing high-performance optoelectronic devices through tailored vdW heterostructures.