Abstract
The epitaxial growth of Ge on Si(111) covered with the 0.3 nm thick SiO2 film is studied by scanning tunneling microscopy. Nanoareas of bare Si in the SiO2 film are prepared by Ge deposition at a temperature in the range of 570℃-650℃ due to the formation of volatile SiO and GeO molecules. The surface morphology of Ge layers grown further at 360℃-500℃ is composed of facets and large flat areas with the Ge(111)-c(2 × 8) reconstruction which is typical of unstrained Ge. Orientations of the facets, which depend on the growth temperature, are identified. The growth at 250℃-300℃ produces continuous epitaxial Ge layers on Si(111). A comparison of the surface morphology of Ge layers grown on bare and SiO2-film covered Si(111) surfaces shows a significantly lower Ge-Si intermixing in the latter case due to a reduction in the lattice strain. The found approach to reduce the strain suggests the opportunity of the thin continuous epitaxial Ge layer formation on Si(111).
Highlights
Further development of optoelectronics and photonics can be associated with the fabrication of integrated devices based on III-V semiconductors grown on Si substrates [1,2]
The surface morphology of Ge layers grown further at 360 ̊C - 500 ̊C is composed of facets and large flat areas with the Ge(111)-c(2 × 8) reconstruction which is typical of unstrained Ge
A comparison of the surface morphology of Ge layers grown on bare and SiO2-film covered Si(111) surfaces shows a significantly lower Ge-Si intermixing in the latter case due to a reduction in the lattice strain
Summary
Further development of optoelectronics and photonics can be associated with the fabrication of integrated devices based on III-V semiconductors grown on Si substrates [1,2]. The preparation of continuous thin GaAs layers by their growth on the bare Si surfaces is impeded because of the large lattice mismatch (~4%) between GaAs and Si. The growth occurs through the StranskiKrastanov growth mode, leading to the formation of three-dimensional islands. The method is based on the use of Si surfaces covered with the ultrathin SiO2 film Ge deposition on such surfaces at rather high temperatures results in the formation of bare Si nanoareas with the size depending on the amount of deposited Ge and temperature [22,23,24,25]. The bare Si nanoareas serve for the epitaxial growth of semiconductor materials which can form a continuous layer due to the island nucleation and growth over the residuals of the SiO2 film. The influence of the technological parameters, such as growth temperature and Ge coverage on the structure and the surface morphology of the grown Ge layers, is examined using scanning tunneling microscopy
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