多孔硅的拉曼光谱研究

本文研究了多孔硅的拉曼光谱随激发激光功率的变化 ,发现当激发光的功率较低时 ,多孔硅的拉曼光谱在 5 2 0cm- 1附近为一单峰。随着激光功率的增加 ,该单峰向低波数移动且半高宽增大 ,当继续增大激光功率时 ,该单峰分裂为双峰 ,位于低波数一侧的拉曼峰随着激光功率的增大而进一步向低波数移动。多孔硅的拉曼光谱随着激光功率的变化是一个可逆的过程。这一结果表明 ,低波数拉曼峰的位置既不能作为多孔硅颗粒尺寸的量度 ,也不能只把低波数的拉曼峰作为多孔硅的特征。我们认为激光诱导多孔硅中LO和TO声子模的简并解除是观察到双峰的主要原因。

Raman Spectroscopic Study of Porous Silicon

Raman spectroscopy of porous silicon with different laser power excitation has been studied It is found that a single Raman band around 520cm -1 appears with a weaker laser excitation while the Raman band sprits into two bands with a stronger laser excitation The band at the lower wavenumber side shifts further to lower wavenumbers with increasing the laser power and the process is reversible when the laser power is reduced The results show that it is unreasonable to assign only the band at the lower wavenumber side to porous silicon and to use this band to calculate the size of the microstructures in porous silicon We attribute the appearance of the double bands to the laser induced non degeneracy of LO and TO phonons