Fabrication of ZnMn2O4 spinel thin film devices for solar-blind ultraviolet photodetectors: Effect of Zn2+ concentration

• Published in: Journal of materials science. Materials in electronics 2023-02, Vol.34 (6), p.514, Article 514
• Main Authors: Agrohiya, Sunil, Dahiya, Sajjan, Rawal, Ishpal, Goyal, Parveen Kumar, Ohlan, Anil, Punia, Rajesh, Maan, A. S.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Devices; Electron microscopes; Field emission microscopy; Manganese oxides; Materials Science; Optical and Electronic Materials; Photometers; Quantum efficiency; Raman spectroscopy; Recovery; Silicon substrates; Sol-gel processes; Spin coating; Spinel; Thin films; Ultraviolet detectors; Ultraviolet radiation; Wavelengths; Zinc compounds
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-023-09883-w

Ultra-violet photodetectors based on ZnMn 2 O 4 spinel have been fabricated on silicon substrates using the sol–gel spin coating technique. XRD and Raman spectroscopy studies reveal that a composite with two mixed phases, Mn 2 O 3 and ZnMn 2 O 4 is formed with the addition of 5 percent Zn to Mn 2 O 3 . This mixed phase ultimately converts into pure ZnMn 2 O 4 spinel phase at higher Zn concentrations (10 and 15 percent). This transformation is clearly visualized in the field emission scanning electron microscope (FESEM)and high-resolution transmission electron microscope (HRTEM) images. The ultraviolet (UV) photodetection behavior of the fabricated devices has been analyzed under the illumination of UV light of wavelengths 365 and 254 nm. It has been found that pristine Mn 2 O 3 is almost inactive towards both wavelengths; however, the incorporation of Zn 2+ in Mn 2 O 3 leads to a significantly large photoresponse of ~774%, 2162%, and 6459% for 5, 10, and 15 percent Zn 2+ concentrations, respectively. The device parameters such as external quantum efficiency (EQE), detectivity, responsivity, and Linear dynamic range (LDR), are found to be improved by increasing the Zn 2+ concentration. The response and recovery times for the fabricated devices are less than 1 s. The ultralow response and recovery times along with excellently high photoresponses of the fabricated devices, make them suitable devices for next-generation photodetectors.