The Photoluminescence Of Silicon Quantum Dots And Coupled With Microdisks

Being quasi-zero dimensional semiconducting material,silicon quantum dots exhibit strong photoluminescence with high efficiency because of the quantum confinement effects as comparing with its bulk counterpart.Silicon quantum dots have numerous advantages over other traditional colloidal quantum dots like CdS or PbSe.Its low toxicity,compatibility with modern electronic industry and high abundance in nature make silicon a very potential candidate for plenty of applications such as optoelectronics,photovoltaic and biomedical imaging.Here we investigated the photoluminescence spectroscopy of silicon quantum dots under different conditions and coupled with micro disks,the results are as following:1.The power dependent photoluminescence of silicon quantum dots both at room temperature and low temperature(20K)were measured.A blue shift in peak energy of photoluminescence has been observed with an increase of laser power.The observed blue shift is attributed to the State Filling Effect.The decrease in line widths with increasing laser power has also been observed.This anomalous behavior is attributed to two different photoluminescence mechanisms involved.2.The photoluminescence of silicon quantum dots coupled with micro disks was investigated by using a confocal system.An enhancement of 30 folds in photoluminescence intensity has been achieved in comparison with uncoupled quantum dots.This enhancement is attributed to the increased collection efficiency by micro disk.3.A comprehensive study has been carried out on silicon quantum dot under different conditions to find out the physical mechanism of the photo-degradation.We conclude that the air accelerates the process of photo-degradation caused by photo-oxidation and photo-bleaching.In vacuum,the photo-degradation process is suppressed because of the suppression in photo-oxidation and photo-bleaching.At low temperature(20K)and low laser power the photoluminescence shows no photo-degradation.