Enhancement in optoelectronic properties of europium-doped ZnS thin films prepared by nebulizer spray technique for UV photodetection applications

In this work, structural, optical, photoluminescence, and photoconductivity properties of Eu3+ (0, 1, 3, and 5%) doped ZnS thin films are investigated. These thin films are fabricated by a low-cost spray pyrolysis method. The structural studies confirm the single-phase nature of pure and Eu3+ doped ZnS thin films and these films crystallize into hexagonal wurtzite structure. Optical properties disclose the semiconductor behavior of the films. The optical bandgap (Eg) values of the films are found to be 3.66, 3.62, 3.50, and 3.55 eV for ZnS, ZnS:Eu (1%) ZnS: Eu (3%) and ZnS:Eu (5%), respectively. Photoluminescence spectra of the films exhibit a high intensity visible and broad UV emission band centered at the wavelengths of 487 and 400 nm, respectively. ZnS:Eu (3%) photo detector exhibits high responsivity, external quantum efficiency (EQE), and detectivity of 1.12 x 10-2 AW11, 3.59% and 4.86 x 109 Jones, respectively among all the fabricated films. The present study reveals that Eu3+ doped ZnS thin film especially around 3% concentration of Eu3+ can be a potential candidate for technological applications in the semiconductor optoelectronic field.

Automated summary

This study investigates the structural, optical, photoluminescence, and photoconductivity properties of Eu3+ doped ZnS thin films. The results show that the films have a single-phase structure and exhibit semiconductor behavior. The lowest optical bandgap is observed at a doping concentration of 3% Eu3+. The films show high intensity visible and UV emission in the photoluminescence spectra. Among all the films, the ZnS: Eu (3%) thin film has the highest photoconductive performance.