Efficient broadband light sensing with anisotropic Sb2S3 based thin film heterojunction photodetectors under self-driven conditions

Abstract

Sb₂S₃ is gaining attention due to its optoelectronic properties required for photovoltaic applications including photodetectors. However, Sb₂S₃ based photodetectors were limited to UV to visible light detection due to its wide energy bandgap of 1.7 eV. Broadband (UV-vis-NIR wavelength) detection is feasible by forming a wide bandgap p-type Sb₂S₃- and a narrow bandgap n-type semiconductor-based heterojunction device. This work first evaluates the structural, optical and electrical properties of Sb₂S₃ films prepared by thermal evaporation and post-sulfurization. Subsequently, n-Si/p-Sb₂S₃ photodetectors were fabricated using the as-deposited and post-sulfurized Sb₂S₃ films to explore their broadband light sensing characteristics. The photodetectors were tested in a broadband wavelength range, under white light and 655 nm illumination conditions with varying intensities for comprehensive analysis. Under self-driven conditions, the n-Si/p-Sb₂S₃ devices demonstrated good responsivity and detectivity in the wavelength range of 350–1100 nm, with a pronounced response in the near-infrared region. A high responsivity of 113 mA W⁻¹, a detectivity of 2.58 × 10¹² Jones and a rise/fall time of 5.2/7.5 ms were observed under 655 nm illumination at 1 µW cm⁻², demonstrating huge potential for self-driven weak light and broadband photodetection applications.