Dynamic Surface evolution and scaling studies on TiO2 thin films by Ti ion implantation

Abstract

The surface dynamics of TiO2 thin films, evolving under the implantation of 50 keV Ti ions, have been investigated. The morphological evolution, as investigated with atomic force microscopy, delineates a surface smoothening by ion implantation.The nanoscale structures at surfaces also undergo a size reduction. Scaling formalism has been applied to understand this temporal and spatial dynamics by estimating the scaling exponents (α,β and γ) via Height-height correlation function (HHCF) and power spectral density (PSD) investigations. The roughness exponent α (0.5 < α < 1) indicates these ion irradiated surfaces to be of self affine nature. Also, they evolve into locally smoother surfaces with increasing fluence. Negative growth exponent (β) also delineates surface smoothening. Exponent, γ, is observed to increase from ~2 at lower ion fluences to 2.5 at the highest fluence. This behavior suggests that diffusion is predominantly controlling the dynamical evolution of the ion irradiated TiO2 surfaces at the highest fluence, similar to that in the bulk case.