Different growth mechanisms of Ge by Stranski-Krastanow on Si (111) and (001) surfaces: An STM study

Structural and morphological features of the wetting layer formation and the transition to the threedimensional Ge growth on (111) and (100) Si surfaces under quasi-equilibrium growth conditions were studied by means of scanning tunneling microscopy. The mechanism of the transition from the wetting layer to the three-dimensional Ge growth on Si was demonstrated. The principal differences and general trends of the atomic processes involved in the wetting layers formation on substrates with different orientations were demonstrated. The Ge growth is accompanied by the Ge atom redistribution and partial strain relaxation due to the formation of new surfaces, vacancies and surface structures of a decreased density. The analysis of three-dimensional Ge islands sites nucleation of after the wetting layer formation was carried out on the (111) surface. The transition to the three-dimensional growth at the Si(100) surface begins with single {105} facets nucleation on the rough Ge(100) surface. (C) 2016 Elsevier B.V. All rights reserved.