Ion induced controlled modifications in structural and optical properties of indium oxide thin films – studies with 25‐keV Co− and N+ beam implantations

Abstract

Two sets of indium oxide thin films (~150 nm) grown on quartz substrates using thermal evaporation technique were processed separately with 25‐keV Co− and N+ ions with several fluences ranging from 1.0 × 1015 to 1.0 × 1016 ions/cm2. The pristine and the ion implanted films were characterized by Rutherford backscattering spectroscopy (RBS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV–Vis spectrometry. The RBS spectra reveal signature of only cobalt and nitrogen in accordance to their fluences confirming absence of any contamination arising due to ion implantation. An increase in the average crystallite size (from 13.7 to 15.3 nm) of Co− ions implanted films was confirmed by XRD. On the other hand, the films implanted with N+ ions showed a decrease in the average crystallite size from 20.1 to 13.7 nm. The XRD results were further verified by SEM micrographs. As seen in AFM images, the RMS surface roughness of the samples processed by both ion beams was found to decrease a bit (29.4 to 22.2 nm in Co− implanted samples and 24.2 to 23.3 nm in N+ implanted samples) with increasing fluence. The Tauc's plot deduced from UV–visible spectroscopy showed that the band gap decreases from 3.54 to 3.27 eV in Co− implanted films and increases from 3.38 to 3.58 eV for films implanted with N+ ions. The experimental results suggest that the modifications in structural and optical properties of indium oxide films can be controlled by optimizing the implantation conditions. Copyright © 2017 John Wiley & Sons, Ltd.