Optical Properties of Amorphous Silicon Quantum Dots(a-Si QDs) with various dot size using Extended H\"uckel Theory

TL;DR

This study uses extended Hückel theory to analyze how the optical properties of amorphous silicon quantum dots change with size, demonstrating a quantum confinement effect that causes a blue shift in absorption spectra.

Contribution

It applies extended Hückel calculations to predict size-dependent optical properties of amorphous silicon quantum dots, highlighting quantum confinement effects.

Findings

Absorption peak shifts from 2.278 eV to 3.856 eV as dot size decreases.

Quantum confinement causes a blue shift in optical absorption.

Smaller dots exhibit higher energy absorption spectra.

Abstract

A high quality amorphous silicon (a-Si) nanostructures has grown experimentally to study the origin of light emission and the quantum confinement effect in a-Si. The quantum confinement effect increases the band gap of material as the size of quantum structure decreases, which results in a blue shift in optical luminescence and energy absorption. Here we demonstrate this effect using extended H\"uckel method to calculate fundamental band gap and optical absorption energy of a-Si samples with various dot sizes. As result, when the dot size was decreased from 2.2 to 1.0 nm, the absorption spectra peak shifted toward higher energy from 2.278 eV to 3.856 eV.