Emission spectra of p-Si and p-Si:H models generated by ab initio molecular dynamics methods

TL;DR

This study uses ab initio molecular dynamics to generate silicon models and simulate their emission spectra, revealing how structural features influence emission properties in p-Si and p-Si:H materials.

Contribution

It introduces a computational approach to simulate emission spectra of porous silicon models and compares results with experimental data, highlighting factors affecting emission.

Findings

Emission spectra maxima relate to silicon backbone size in p-Si.

Hydrogen concentration influences emission in p-Si:H.

Quantum confinement explains p-Si emission, but other theories are needed for p-Si:H.

Abstract

We created 4 p-Si models and 4 p-Si:H models all with 50% porosity. The models contain 32, 108, 256 and 500 silicon atoms with a pore parallel to one of the simulational cell axes and a regular cross-section. We obtained the densities of states of our models by means of ab initio computational methods. We wrote a code to simulate the emission spectra of our structures considering particular excitations an decay conditions. After comparing the simulated spectra with the experimental results, we observe that the position of the maximum of the emission spectra might be related with the size of the silicon backbone for the p-Si models as the quantum confinement models say and with the hydrogen concentration for the p-Si:H structures. We conclude that the quantum confinement model can be used to explain the emission of the p-Si structures but, in the case of the p-Si:H models it is necessary to consider others theories.