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在室温和非共振条件下,测量了超短周期(1—3个单层)GaAs/AlAs超晶格的 Raman散射光谱.样品用分子束外延方法生长在(001)晶向的半绝缘 CaAs衬底上.实验结果表明,在这种超短周期超晶格中存在两种作用:一种是光学声子的限制效应,另一种是混晶化效应.对于单层超晶格,在各种散射配置下的 Raman光谱都与Al(0.5)Ga_(0.5)As三元混晶的Raman光谱十分相似.而对于4个单层或者更厚的超晶格样品,混晶化效应基本可以忽略,仅仅表现为界面效应,光学声子的限制效应起主导作用.
The Raman scattering spectra of superlattice (1-3 single layers) GaAs / AlAs superlattices were measured at room temperature and non-resonant conditions.The samples were grown in a (001) orientation semi-insulating CaAs liner by molecular beam epitaxy The experimental results show that there are two kinds of effects in this ultra-short period superlattice: one is the limiting effect of optical phonon and the other is the effect of mixed crystallization.For the single-layer superlattice, The Raman spectra of all kinds of scattering configurations are very similar to those of Al (0.5) Ga 0.5 As As mixed crystals, while for four single layers or thicker superlattice samples, the mixed crystallization effect can be neglected , Only for the interface effect, the limiting effect of optical phonon plays a leading role.