Effect of progressive oxidation on the optical properties of small silicon quantum dots: A computational study

Abstract

Studies of oxidation processes of small silicon quantum dots (Si-QDs) have generally concerned either isolated surface sites or the effect of full oxide shell or hydroxyl passivation. In this study we report the results from density-functional calculations examining the effect of a progressive oxidation of a Si-QD, either via insertion into Si-Si bonds or by replacement of surface Si-H bonds with Si-(OH). The calculations reveal that oxide formation is favored over hydroxyl surface passivation, increasing oxide and hydroxyl exhibit qualitatively different effects on the optical gap, and for the current choice of Si-QD only high levels of oxygen incorporation lead to a significant blueshift in absorption.