Optical Properties of Pure and Mixed Germanium and Silicon Quantum Dots

TL;DR

This study uses advanced computational methods to analyze the optical properties of pure and mixed silicon and germanium quantum dots, revealing their potential for band gap engineering and confirming quantum confinement effects.

Contribution

It provides detailed computational analysis of pure and mixed Ge/Si quantum dots using high-accuracy DFT and TDFT, highlighting their versatility for band gap tuning.

Findings

Mixed Ge/Si quantum dots have tunable band gaps between pure Si and Ge dots.

Results support the quantum confinement theory for all studied quantum dots.

The hybrid DFT functional B3LYP effectively models optical properties of QDs.

Abstract

We study the optical properties of hydrogen passivated silicon, germanium and mixed Ge/Si core/shell quantum dots (QDs) using high accuracy Density Functional Theory (DFT) and time-dependent DFT (TDFT). We employ the hybrid DFT functional of Becke, Lee, Yang and Parr (B3LYP) in combination with good quality basis sets. As we have shown in our previous work, this combination is an accurate and computationally efficient way for such calculations. The mixed quantum dots, as would be expected, are more versatile and offer more possibilities for band gap engineering, with gap values (electronic and optical) between those of the corresponding Si and Ge dots. Our results support the quantum confinement theory for all three types of QDs.