POLARIZED RAMAN SPECTROSCOPY OF SINGLE LAYER AND MULTILAYER Ge/Si(001) QUANTUM DOT HETEROSTRUCTURES

摘要

Polarized Raman spectroscopy in backscattering geometry has been applied here for investigation of Ge/Si(001) quantum dot multilayer stmctures (ranging from 1 to 20 layers) grown by the Stranski-Krastanov technique. The characteristic Raman spectra of Ge dots have been obtained by taking the difference between the Raman spectra of the dots sample and the reference Si substrate, registered with the same polarization in the scattering channel. We found that Raman spectra of Ge dots obtained in such a manner are strongly polarized, in particular for Si-Ge (at -413 cm~(-1)) and Ge-Ge (at -295 cm~(-1)) vibrational modes. The dependence of peak intensity and peak position of Si-Ge and Ge-Ge modes versus the number of Ge dot layers, and versus the growth temperature for single layers, have been studied. The intermixing effect and stress have been obtained using the ratio of the integrated intensities and the peak positions of the aforementioned bands.