Swift heavy ion-induced surface nanopatterning of indium oxide films

Abstract

In this study, indium oxide films are deposited by electron-beam evaporation and thermally annealed at 600°C in an oxygen atmosphere to form stoichiometric In₂O₃ films with a high transparency. They are then irradiated with 120 MeV Ag ions with different fluences (i.e. 1×10¹¹, 1×10¹² and 1×10¹³ ions/cm²). The morphology of the films as a function of fluence is studied by atomic force microscopy and the root mean square roughness values are obtained. The pristine film consists of uniformly-sized particles distributed over the sample surface. On irradiation with 1×10¹¹ ions/cm², fragmentation of these particles takes place. These fragmented particles start to agglomerate and align slightly in a particular direction at a fluence of 1×10¹² ions/cm². Morphology is further confirmed by scanning electron microscopy. A two-dimensional power spectral density analysis has been done to elucidate the topographical changes due to varying ion fluences. The growth exponent value of α>1 suggests that the growth is governed by surface diffusion.

Keywords:

• indium oxide
• swift heavy ions
• atomic force microscopy
• power spectral density

Acknowledgements

This work was supported by grants from Inter-University Accelerator Centre (UFUP # 43301 “SHI-induced modifications in In₂O₃ thin films”) and Delhi University R&D Grant. We acknowledge Department of Science and Technology, Government of India, providing funding for AFM and SEM facility at IUAC, New Delhi. One of us (N.T.) acknowledges the grant of fellowship from UFUP # 43301. We are thankful to D.K. Avasthi for many useful discussions and encouragement in this work.