Abstract
A kinetic diagram of Ge growth on Si is constructed by methods of fast electron diffraction and scanning electron microscopy. Activation energies of morphological transitions from two-dimensional to three-dimensional growth and from hut-clusters to dome-type islands are determined. The curve of the 2D–3D transition has two segments that follow the Arrhenius law and refer to different mechanisms of two-dimensional growth: two-dimensional island mechanism in the temperature range of 300–525 °C with the activation energy of −0.11 eV and step motion in the temperature range of 525–700 °C with the activation energy of 0.15 eV. Transitions from hut-islands to dome-islands are also observed. The curve constructed for the hut-dome transition is approximated by two exponential segments that obey the Arrhenius law. The hut-dome transition activation energy is 0.11 eV in the temperature range of 350–550 °C and 0.24 eV in the temperature range of 550–700 °C. The maximum density of islands in the case of Ge growth on a Ge x Si1−x layer reaches 4 · 1011 cm−2. An increase in the composition leads to an increase in the density of Ge islands owing to a decrease in the length of migration of Ge adatoms on the Ge x Si1−x surface, as compared to the case of Ge growth on Si. The periodicity N, which is manifested as a (2 × N) superstructure, decreases during the reconstruction from 14 to 8 with increasing Ge content in the Ge x Si1−x layer. An increase in thickness or temperature leads to a decrease in periodicity and testifies to Ge segregation; in this case, stress relaxation occurs, which reduces the Ge diffisivity.
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Original Russian Text © A.I. Nikiforov, V.A. Timofeev, S.A. Teys, O.P. Pchelyakov, 2014, published in Avtometriya, 2014, Vol. 50, No. 3, pp. 5–12.
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Nikiforov, A.I., Timofeev, V.A., Teys, S.A. et al. Formation of Ge/Si and Ge/Ge x Si1−x /Si nanoheterostructures by molecular beam epitaxy. Optoelectron.Instrument.Proc. 50, 217–223 (2014). https://doi.org/10.3103/S8756699014030017
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DOI: https://doi.org/10.3103/S8756699014030017