Relaxation and derelaxation of pure and hydrogenated amorphous silicon during thermal annealing experiments

TL;DR

This study investigates the structural relaxation and derelaxation processes in pure and hydrogenated amorphous silicon during thermal annealing, revealing differences in strain relaxation mechanisms through spectroscopy and calorimetry.

Contribution

It provides new experimental evidence on the relaxation behaviors of a-Si and a-Si:H, especially highlighting the derelaxation of bond angle strain in hydrogenated silicon.

Findings

Heat evolved from a-Si:H is due to derelaxation of bond angle strain.

Relaxation states after annealing are similar for pure and hydrogenated silicon.

Supports the predicted configurational gap between a-Si and crystalline silicon.

Abstract

The structural relaxation of pure amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) materials, that occurs during thermal annealing experiments, has been analysed by Raman spectroscopy and differential scanning calorimetry. Unlike a-Si, the heat evolved from a-Si:H cannot be explained by relaxation of the Si-Si network strain, but it reveals a derelaxation of the bond angle strain. Since the state of relaxation after annealing is very similar for pure and hydrogenated materials, our results give strong experimental support to the predicted configurational gap between a-Si and crystalline silicon.