Self-Powered, High-Speed Photodetection Using Sn (5%) Doped Nanocrystalline CdS Thin Films Deposited by Vacuum Evaporation on FTO

Baljinder Singh^1, , Mayank Arora² and Krishan Kumar³

¹Department of Physics, S. D. (PG) College, Panipat-132103, Haryana, India

²Department of Chemistry, S. D. (PG) College, Panipat-132103, Haryana, India

³Department of Physics, Sanatan Dharma College, Ambala Cantt. -133001, Haryana, India

Cite this paper:
Baljinder Singh, Mayank Arora and Krishan Kumar. Self-Powered, High-Speed Photodetection Using Sn (5%) Doped Nanocrystalline CdS Thin Films Deposited by Vacuum Evaporation on FTO. Journal of Materials Physics and Chemistry. 2025; 13(1):22-28. doi: 10.12691/jmpc-13-1-4

Abstract

This work presents the fabrication and comprehensive characterization of a self-powered, high-speed photodetector based on an FTO/nanocrystalline CdS:Sn 5% heterojunction. Tin-doped CdS thin films were deposited onto FTO-coated glass substrates using thermal evaporation coupled with inert gas condensation. XRD analysis revealed the polycrystalline nature of the nc-CdS:Sn 5% thin films with peaks corresponding to the hexagonal CdS phase. Raman spectroscopy showed characteristic phonon modes of CdS, while FE-SEM displayed densely packed grains with uniform morphology. EDAX confirmed the elemental composition with Cd, S, and Sn in the desired stoichiometric ratios. The resulting device exhibited pronounced rectifying behavior in the dark, alongside significant photovoltaic effects under illumination. Key device metrics included a sensitivity of 0.25, a responsivity of 1.62 µA/W, and a detectivity of 1.51 × 10⁶ Jones at zero bias, measured under white light irradiation. Dynamic response evaluation revealed reproducible operation up to 700 Hz, with fast rise and fall times of 0.07 µs and 2.56 µs, respectively. These findings underscore the promising potential of the FTO/CdS:Sn 5% heterojunction for high-speed optical communication, self-powered optical switching, and advanced optoelectronic applications.

Keywords:
nanocrystalline CdS FE-SEM heterojunction self-powered photodetector optoelectronics

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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