Abstract
The photoluminescence (PL) of the combined Ge/Si structures representing a combination of large (200–250 nm) GeSi disk-like quantum dots (nanodisks) and four-layered stacks of compact groups of smaller (30 nm) quantum dots grown in the strain field of nanodisks was studied. The multiple increase in the PL intensity was achieved by the variation of parameters of vertically aligned quantum dot groups. The experimental results were analyzed on the basis of calculations of energy spectra, electron and hole wave functions. It was found that the quantum dot arrangement in compact groups provides the effective electron localization in Δx,y-valleys with an almost equal probability of finding an electron in the Si spacer and Ge barrier. As a result, the main channels of radiative recombination in the structures under study correspond to spatially direct optical transitions.
Highlights
There is a considerable interest in the search for possible ways of creating the light-emitting devices based on the silicon technology[1,2,3,4,5,6,7,8,9]
If quantum dots (QDs) groups are grown at the surface of nanodisk, the effective localization of Δx,y-valley electrons can not be realized because the strain field above the nanodisk promotes only the Δz-valley electron localization
For scanning tunneling microscopy (STM) studies, the test uncovered QD structures were grown in the same conditions
Summary
There is a considerable interest in the search for possible ways of creating the light-emitting devices based on the silicon technology[1,2,3,4,5,6,7,8,9]. This paper is aimed at developing the light-emitting structures based on a Ge-Si heterosystem containing the compact groups of closely spaced QDs formed during the molecular beam epitaxy (MBE) on the strain-patterned substrates. The main idea is to use the built-in strain for controlling the spatial localization of charge carriers, their energy spectrum and overlapping between electron and hole wave functions This is possible because of the exclusive role that the strain plays in the band alignment in Ge/Si heterostructures. At this distance, the strain distribution on the surface of growing layer allows one to form the compact QD groups containing two or three coupled hut-clusters with the alignment of the longest QD edges. Such QD groups configuration is very similar to the one observed in the double QD structures studied in ref
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
