摘要
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.
Room temperature Raman spectra of super short period GaAs/AlAs superlattices underoffresonance conditions are reported.Samples were grown by MBE method on (001) orientedsemi-insulating GaAs substrates.Our experimental results show that there are two effects:confinement effect of optical phonons and alloy effect,It is found that Raman spectra of onemonolayer superlattice measured in various scattering configurations are very similar to those ofAl_(0.5)Ga_(0.5)As triple alloy.In the case of monolayer numbers≥4, however, confinement effectof the optical phonons is prominent, while the alloy effect is only shown as interface effect andcan be neglected.
基金
国家自然科学基金
