The formation of intermediate layers in covered Ge/Si heterostructures with low-temperature quantum dots: a study using high-resolution transmission electron microscopy and Raman spectroscopy
Abstract
The method of software analysis of high-resolution TEM images using the peak pairs algorithm [Galindo P L et al 2007 Ultramicroscopy 107 1186-93] in combination with Raman spectroscopy was employed to study lattice deformations in Ge/Si(001) structures with low-temperature Ge quantum dots. It was found that the stresses do not spread in a thick Si layer above quantum dots, but completely relax via the formation of a thin boundary layer of mixed composition. However, intermixing of Ge and Si is absent beneath the Ge layer in samples with a Ge coverage of 10 Å. Besides intermixing was not observed at all, both beneath and above the Ge layer, in samples with a Ge coverage of 6 Å or less. This may be due to the predominance of Ge diffusion into the Si matrix from the {105} facets of Ge huts, not from the Ge wetting layer, at low temperatures of the Ge/Si structure deposition. The critical thickness of Si coverage at which the intense stress-induced diffusion takes place is determined to lie in the range from 5 to 8 nm.
- Publication:
-
Semiconductor Science Technology
- Pub Date:
- April 2020
- DOI:
- 10.1088/1361-6641/ab73f1
- arXiv:
- arXiv:1907.07169
- Bibcode:
- 2020SeScT..35d5012S
- Keywords:
-
- Ge/Si quantum dots;
- lattice deformation;
- strain relaxation;
- HR TEM;
- peak-pairs analysis;
- Raman scattering;
- Condensed Matter - Materials Science
- E-Print:
- 18 pages, 9 figures