Swift heavy ion induced modifications in the structural, optical and methane sensing properties of indium oxide thin films - A comparative study using Ag9+ and O7+ ion irradiation

¹Department of Physics, Jamia Millia Islamia, New Delhi 110025, India

²Special Center for Nanosciences, Jawaharlal Nehru University, New Delhi 110067, India

³Amity Institute of Nanotechnology, Noida, Uttar Pradesh 201313, India

Adv. Mater. Lett., 2018, 9 (7), pp 481-487

DOI: 10.5185/amlett.2018.2033

Publication Date (Web): Jun 14, 2018

Copyright © IAAM-VBRI Press

E-mail: amsiddiqui@jmi.ac.in

Abstract

Thin films of indium oxide grown on quartz substrates were subjected to 100 MeV Ag⁹⁺ and O⁷⁺ ions irradiation. The pristine and swift heavy ions irradiated films were characterized using X-ray Diffraction, Rutherford Backscattering Spectrometry, Scanning Electron Microscopy and UV-Vis Spectroscopy to examine the effect of irradiation with ions having large difference in the values of electronic energy loss (S_e) on the structural, microstructural and optical properties of indium oxide thin films. XRD and SEM studies revealed deterioration in crystallinity along with decrease in both crystallite size and grain size upon irradiation with both Ag⁹⁺ and O⁷⁺ ions. However, the decrease in the crystallite size and grain size in comparison to the pristine film was more radical for irradiation with Ag⁹⁺ ions. RBS spectra suggest that the electronic sputtering in the indium oxide films due to SHI irradiation is very less. AFM images illustrate the decrease in surface roughness from 29.8 nm for the pristine film to to 27.4 nm and 26.7 nm on irradiation with 100 MeV O⁷⁺ and Ag⁹⁺ ions at a fluence of 3.3×10¹³ ions/cm².  Also, UV-Vis study revealed an increment in the value of optical band gap from 3.41 eV for the pristine film to 3.53 and 3.67 eV for indium oxide films irradiated with of 3.3×10¹³ ions/cm² fluence of O⁷⁺ and Ag⁹⁺ ions respectively. The irradiation induced structural and optical modifications have been explained using the Thermal spike model. Along with the structural and optical properties, sensing properties of the pristine and irradiated films for 100 ppm methane gas at an operating temperature of 300^oC have also been examined and the results have been correlated with the induced structural modifications.

Keywords

Indium oxide, swift heavy ions, electronic energy loss, thermal spike, gas sensing.