Improved Light Absorption by Quantum Confinement and Band Folding: Enhanced Efficiency in Silicon Based Solar Cells

TL;DR

This paper explores how quantum confinement and band folding in Si/BeSe0.41Te0.59 heterostructures can enhance light absorption, potentially improving silicon solar cell efficiency through theoretical analysis of electronic and optical properties.

Contribution

It introduces a theoretical study combining simple and semiempirical methods to demonstrate enhanced light absorption in specific silicon-based heterostructures for solar cells.

Findings

Light absorption can be improved in a single quantum well up to 20 Å thick.

Interface states appear within the silicon band gap, facilitating optical transitions.

Optical edges are near the silicon band gap, with allowed transitions.

Abstract

The improvement of light absorption in Si/BeSe$_{0.41}$Te$_{0.59}$ heterostructures for solar cell applications is studied theoretically. First, using simple approaches we found that light absorption could be improved in a single (uncoupled) quantum well with a thickness up to 20 {\AA}. Second, by semiempirical tight-binding methods we calculated the electronic structure and optical properties of various (Si$_{2})_{n}$/(BeSe$_{0.41}$Te$_{0.59})_{m}$ [001] superlattices. Two bands of interface states were found in the band gap of bulk Si. Our calculations indicate that the optical edges are close to the fundamental band gap of bulk Si and the transitions are optically allowed.