Remarkable fast-response visible light photodetectors based on SnS thin films on silicon substrates

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2025, Vol.131 (1), Article 80
• Main Authors: V. P., Priyanka, Venkatesh, R., Hegde, S. S., Valanarasu, S., Nivedhitha, K. S., Banapurmath, N. R.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Electric contacts; Incident light; Luminous intensity; Machines; Manufacturing; Morphology; Nanotechnology; Optical and Electronic Materials; Optical properties; Photoelectric effect; Photometers; Physics; Physics and Astronomy; Processes; Quantum efficiency; Recovery time; Silicon substrates; Silicon wafers; Silver; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-024-08189-w

Thin films of tin sulfide (SnS) were deposited on the silicon wafer substrates via thermal evaporation technique. To achieve high performance in the fabricated visible light photodetectors (PDs), the structure, morphology, composition, and the optical characteristics of the SnS films were investigated by varying the substrate temperature over a range of 120–270 o C. X-ray diffraction (XRD) and Raman studies indicated the formation of an orthorhombic SnS phase. Phase-pure SnS thin films of enhanced crystallinity were obtained for relatively low substrate temperature of 170 o C. SEM images confirmed vertically grown grain surface morphology, and the surface of the film was compact with densely packed large grains at a substrate temperature of 170 o C. The optical properties of the deposited films were analyzed from the diffuse reflectance spectroscopy (DRS) measurements. Photodetectors (PDs) are fabricated using metal masks and making thermally evaporated silver (Ag) electrical contact onto SnS thin films. Photoresponse properties of all the photodetectors were tested using a 532 nm laser source of different power densities (1–5 mW/cm 2 ) under dark and illumination conditions. I-V characterization of PDs indicated excellent photocurrent (I PC ) of 18.66 µA under 5 V bias and 5 mWcm − 2 incident light intensity. The performance of the PDs was assessed by estimating responsivity (R), external quantum efficiency (EQE), specific detectivity (D*), and response/recovery time. The best photodetector devices fabricated using films deposited at 170 o C had an upmost responsivity of 36 × 10 − 2 AW − 1 , external quantum efficiency (EQE) of 85%, and a detectivity of 3.58 × 10 10 Jones. Ultra-short response/recovery times of 0.27s/0.27s confirmed the high switching speed of the SnS/Si PDs. The findings of this study demonstrated a promising approach to enhancing the response speed of SnS thin film photodetectors for emerging visible light detection applications.