Single crystal PbTe thin films have been grown on BaF2 (111) by using solid source molecular beam epitaxy. The studies of evolution of the surface morphology with the increasing growth temperature from 375 to 525 degrees C by AFM show that PbTe epilayers exhibit smooth surface morphologies with atomic layer scale roughness and are crack free. It is found that for PbTe grown at 475 degrees C, the morphology is dominated by triangles and the rms roughness is 3.987nm. Compared to the rms roughnesses of 0.432nm and 0.759nm for the samples grown at 375 and 525 degrees C respectively, the surface of the PbTe layer grown at 475 degrees C is much rougher. This roughening transition is due to the interaction between the elastic relaxation and the plastic relaxation during the strain relaxation process. In contrast to the result of the morphology that the PbTe epitaxial layer grown at 375 degrees C has most smooth surface, as observed from the line width of x-ray diffraction curves at higher growth temperature improves the crystal quality of the single-crystalline PbTe layer.
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