GaAs/SiO_2纳米晶镶嵌薄膜的拉曼光谱与吸收光谱研究

Raman Spectra and Optical Absorption Spectra of GaAs/SiO_2 Nanocrystals Embedded Thin Films

采用射频磁控共溅射与高真空退火相结合的方法 ,分别在单晶硅片和光学石英玻璃片上制备了 Ga As/ Si O2 纳米晶镶嵌薄膜样品。激光拉曼光谱的测量结果表明 ,退火态样品 (4 0 0℃ ,6 0 min)的拉曼光谱特征峰呈现宽化和红移 ,红移量为 9.5cm-1,对应薄膜中 Ga As纳米晶粒平均粒径约为 3nm。样品的室温吸收光谱测量结果表明 ,由于受量子限域效应的主导作用 ,与 Ga As块状单晶相比 ,样品光学吸收边呈现出明显的蓝移 ,蓝移量为 1.78e V,而且在吸收光谱上还出现了若干可分辨的吸收峰。

GaAs/SiO 2 nanocrystals embedded thin films have been prepared on silicon (111) wafers and optical silica plates by radio frequency magnetron cosputtering technique and post annealing at 673 K in vacuum. Raman spectroscopy strongly suggest the existence of GaAs nanocrystals being 3 nm in average size dispersed in SiO 2 thin films. Compared with that of the bulk GaAs crystals, the optical absorption edge of GaAs nanocrystals exhibits a blue shift as large as 1 78 eV, and a few absorption peaks, which are mainly caused by the quantum confinement effect.