"Impurity Doping into Semiconductor Nanocrystals"

本课题的研究目标是：1)建立将杂质原子掺杂到半导体纳米晶体中的方法；2)开发用于验证掺杂和估计掺杂程度的分析工具；3)研究掺杂引起的纳米晶体物理性质的变化，特别是光学性质的变化。利用溅射技术可以成功地将B原子和P原子掺杂到Si纳米晶体中。喇曼光谱中fano型干涉的出现证明了掺杂的成功。我们还可以成功地观察到掺杂引起的光致发光光谱的变化。光致发光光谱的变化被认为是由于产生了与杂质态结合的激子。Er和Yb离子也可以掺杂到含有Si纳米晶体的SiO2薄膜中。在Si纳米晶体存在的情况下，Er和Yb表现出较强的发光能力，而在Si纳米晶体不存在的情况下，Er和Yb的发光能力很弱。强光发射是由Si纳米晶体向Er和Yb离子的能量转移引起的。本研究结果提示了硅基发光器件的可能性。

The aims of this research project are, i) to establish the method of doping impurity atoms into semiconductor nanocrystals, ii) develop the analytical tools for verifying the doping and estimate the degree of doping, and iii) investigate the change in physical properties pf nanocrystals caused by doping, in particular, the optical properties.We could successfully dope B and P atoms into Si nanocrystals by applying the cosputtering technique. The success in doping could be verified by the appearance of Fano-type interference in Raman spectra. We could also successfully observe the change in the photoluminescence spectra caused by doping. The change in the photoluminescence spectra is believed to arise from the creation of excitons bound to the impurity states.Er and Yb ions could also be doped into SiO2 thin films containing Si nanocrystals. In the presence of Si nanocrystals, Er and Yb exhibited strong light emission, while the light emission was very weak, in the absence of Si nanocrystals. The strong light emission is caused by the energy transfer from Si nanocrystals to Er and Yb ions. The present results suggest the possibility of Si-based light emitting devices.