How Thermal Annealing Process Determines the Inherent Structure Evolution in Amorphous Silicon: An Investigation from Atomistic Time Scales to Experimental Time Scales

TL;DR

This study investigates how the annealing process influences the evolution of inherent structures in amorphous silicon across atomistic to experimental timescales, revealing different energy barrier regimes and proposing a multi-timescale model.

Contribution

It introduces a novel multi-timescale model based on energy barrier distributions to predict annealing effects beyond conventional simulation limits.

Findings

Energy barrier distributions follow different regimes depending on annealing rate.

Two modes are identified in the energy spectra during annealing.

The proposed model accurately predicts heat release during annealing.

Abstract

The annealing treatment in the advanced manufacturing process, e.g., laser-assisted manufacturing, determines the final state of glasses which is critical to its thermal, electrical and mechanical properties. Energy barriers analysis based on the potential energy surface offers an effective way to study the microscopic evolution of the inherent structures during the annealing process in a broadening timescale range, i.e., from atomistic timescale ( ~ ps) to experimental timescale (~ s). Here, we find the distribution activation energy barriers in the potential energy surface can be divided into three regimes 1, the distribution mainly follows the Rayleigh distribution when the annealing rate Rdot < 1e15 K/s; 2, two different modes, i.e., an exponentially decaying mode and a Rayleigh distribution mode, are found in the spectra when the annealing rate 1e15 K/s < Rdot < instant; 3, the spectra is almost following the exponentially decaying mode when the system is under the instant annealing process. However, the spectra of relaxation energy barriers only show an exponentially decaying mode with a decreasing decay parameter. A multi timescale model for any specific annealing rate, which is beyond the limit of the conventional atomistic simulations, i.e., molecular dynamics simulations, is then proposed based on the distribution of the energy barriers. Such a model enables quantitative explanations and predictions of the heat release during the annealing process of the nanocalorimetry measurements or laser-assisted manufacturing.