Studying the kinetics of microstructure formation through dewetting of As-Se thin films

Abstract

The chalcogenide glasses have always drawn attention in photonics for being the most suitable materials for applications in the infrared region. Although their use in integrated photonics is promising, there are yet many challenges to integrating optical components in nano- and microscale. The dewetting of thin films is a mostly unexplored and attractive alternative to produce self-assembled structures in solid substrates. Chalcogenide glasses are among the few materials to present dewetting below 300 \ifmmode^\circ\else\textdegree\fi{}C. We report the thermal-induced dewetting of ${\mathrm{As}}_{x}{\mathrm{Se}}_{100\text{--}x}$ thin films, deposited by electron beam. The activation energy for dewetting is obtained by analyzing the kinetics of dewetting at different temperatures. This energy is greatly affected by the number of homopolar bonds and the glass dimensionality. As a consequence, the higher activation energy is found in the composition with fewer degrees of freedom $({\mathrm{As}}_{40}{\mathrm{Se}}_{60})$. The rupture mechanism and the size of the droplets are also greatly affected by the glass composition. This study provides an insight on how to control and use dewetting as an alternative route for nano- and microfabrication in photonics.