Raman study of Si–Ge intermixing in Ge quantum rings and dots |
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Authors: | V.I. Mashanov H.-H. Cheng C.-T. Chia Y.-H. Chang |
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Affiliation: | aCenter for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan, ROC;bGraduate Institute of Electronic Engineering, National Taiwan University, Taipei 106, Taiwan, ROC;cDepartment of Physics, National Taiwan Normal University, Taipei 106, Taiwan, ROC;dDepartment of Physics, National Taiwan University, Taipei 106, Taiwan, ROC |
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Abstract: | The Ge/Si (1 0 0) nanostructures have been studied by atomic force microscopy (AFM) and Micro Raman optical spectroscopy. Two layers of Ge of total thickness 0.75 nm and Si cap with thickness 2.5 nm were deposited by the method of molecular beam epitaxy at the temperature range 640–700 °C. AFM shows both quantum dots and ring-shape Ge nanostructures. From the analysis of the intensity and energy shift of the Raman signal we have found that the average concentration of Ge decreases considerably from 44% to 27%, when the growth temperature increases, whereas the degree of strain relaxation remains roughly the same. This allows us to conclude that intermixing is a dominating mechanism for strain relaxation in processes of transformation of Ge quantum dots to quantum rings. |
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Keywords: | Germanium Quantum dots Quantum rings Raman scattering |
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