# Humidity effects on evolution of CsI thin Films: Fractal studies of rough surfaces

## TL;DR

This study examines how humidity exposure affects the morphology, microstructure, composition, and fractal surface properties of CsI thin films, revealing increased grain size, compositional changes, and altered fractal dimensions.

## Contribution

It provides new insights into the effects of humidity on CsI thin films' microstructure and fractal surface characteristics, using comprehensive morphological and fractal analyses.

## Key findings

- Grain size increases after humidity exposure
- Atomic percentage of Cs:I ratio doubles with humidity
- Fractal dimension of surface is affected by humidity

## Abstract

The present work investigates the morphological, micro-structural, compositional and fractal analysis for CsI thin films in case of "as-deposited" and "1 hour humid air aged". The variation of grain sizes obtained from transmission electron microscopy (TEM) technique are found to be in the range of ~ 313 nm to ~ 1058 nm. The average grain size is found to increase after exposing to humidity. The experimental values of interplanner spacing are found to be less than the standard value which signifies that a compressive stress is acting in the film. The elemental compositions of CsI film has been investigated by the means of energy dispersive X-ray spectroscopy (EDAX) technique. The atomic percentage of Cs:I (1:1) is found to be increased by a factor of two after exposing to humidity. The surface morphology of CsI thin films is analyzed by the atomic force microscopy (AFM) for both cases. The fractal analysis is performed on the AFM micrographs. The autocorrelation function and height-height correlation function is used to study the correlation properties of surface and roughness exponent. It is found that the fractal dimension is affected after exposing to humidity.