Solid-State Dewetting Dynamics of Amorphous Ge Thin Films on Silicon Dioxide Substrates.

Dimosthenis Toliopoulos,Monica Bollani,Sergio Bietti,Emiliano Bonera,Marco Abbarchi,Giovanni Isella,Mohammed Bouabdellaoui,Alexey Fedorov,Shiro Tsukamoto,Andrea Ballabio,Stefano Sanguinetti

doi:10.3390/nano10122542

Abstract

We report on the dewetting process, in a high vacuum environment, of amorphous Ge thin films on SiO2/Si (001). A detailed insight of the dewetting is obtained by in situ reflection high-energy electron diffraction and ex situ scanning electron microscopy. These characterizations show that the amorphous Ge films dewet into Ge crystalline nano-islands with dynamics dominated by crystallization of the amorphous material into crystalline nano-seeds and material transport at Ge islands. Surface energy minimization determines the dewetting process of crystalline Ge and controls the final stages of the process. At very high temperatures, coarsening of the island size distribution is observed.

Highlights

Germanium continuous thin films are in a metastable state of equilibrium
The sample series is designed to address the dependence on temperature of the dewetting process dynamics
Models based on surface diffusion, driven by surface energy minimization, predict that, during dewetting, the film material is removed from the substrate and it accumulates in the rim of the receding film [22,23]

Summary

Introduction

Germanium continuous thin films are in a metastable state of equilibrium. As such, they can be transformed into isolated nano-islands or more complex architec-tures by annealing at high temperature [1,2,3]. Solid-state dewetting of monocrystalline ultra-thin silicon on insulator (SOI) and Ge on insulator (GOI) is a scalable fabrication technique that allows the fine tuning of single crystal nano-islands’ size, size dispersion and surface distribution [6,7,8]. In this system, the main mechanisms at play are surface energy minimization and surface diffusion [9,10]. This is an emerging alternative to the wide-ly employed plasmonic particles for the enhancement of light–matter interaction and light management at visible and near infrared frequencies

Methods

Results

Discussion

Conclusion