中文摘要：

采用分子束外延（MBE）方法在BaF2（111）衬底上生长了高质量的PbTe单晶薄膜，拉曼光谱测量观察到了表面氧化物的振动模、布里渊区中心（q=0）纵光学（LO）声子振动模以及声子．等离子激元耦合模振动．随着显微拉曼光谱仪激光光斑聚焦深度的改变，各拉曼散射峰的峰位、积分强度、半高宽等都表现出不同的变化趋势．随着激光光斑聚焦位置从样品表面上方3μm处变化到表面下方3μm处，PbTe外延薄膜的LO声子频率从119cm^-1移动到124cm^-1．MBE原生PbTe样品与表面经腐蚀抛光处理后的样品相比，各散射峰强度的变化也体现出不同的趋势．以上这些现象都与各个拉曼散射峰具有不同的振动起源有关．而PbTe薄膜LO声子产生的频移，则可以从外延膜与衬底间的晶格失配引起的应变和弛豫角度加以解释。

英文摘要：

High quality single crystalline PbTe thin films have been grown on BaF2 （111） by using molecular beam epitaxy（MBE）. Raman scattering measurements have revealed the vibration modes of oxide on the surface, longitudinal optical（LO） phonon at Brillouin center q = O, and coupled plasmon-phonon. With the variation of the focusing-depth（FD） of the pumping laser beam, the integrated intensities, peak positions and line widths of the observed Raman peaks showed different behaviors. When FD changed from 3μm above the top-surface to 3 μm below the bottom-surface, the PbTe LO phonon frequency shifted from 119 to 124 cm^-1 Different Raman scattering results were also observed by comparison of the freshly surface-etched and the as grown PbTe samples. These phenomena originated from the different vibration modes. The frequency shift of LO phonon is explained by the fact that the strain relaxation caused by the lattice mismatch between PbTe and BaF2 is as high as 4.2 %.