writer：Wei Qin, Wen-Cai Lu, Lin-Hua Xia, Li-Zhen Zhao, Qing-Jun Zang, C. Z. Wang
keywords：Si172 QDs; hydrogenated Si172 QDs; optical properites;
source：期刊
specific source：Nanoscale
Issue time：2015年

        The structures and optical properties of silicon quantum dots (QDs) have long been studied. Exploring the growth pattern of silicon crystal is challenging due to the competitions among various structural motifs. Here, about 1.7 ~ 1.9 nm silicon QDs (Si₁₇₂ QDs) have been unbiased searched by genetic algorithm (GA) combined with a tight-binding molecular dynamics (TBMD) method. The optical properties of the bare and hydrogenated Si₁₇₂ QDs have been studied using the time-dependent density functional theory (TD-DFT) calculations. We found that at the inner part of the Si₁₇₂ QDs, a silicon crystal has been formed. Comparing with the bare Si₁₇₂ QDs, the maximum absorption peaks of the hydrogenated Si₁₇₂ QDs have shifted from the near infrared region to the visible region or the ultraviolet region.