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Electronic structure and optical transitions in Sn and SnGe quantum dots in a Si matrix

Moontragoon, P., Vukmirovic, N., Ikonic, Z. and Harrison, P. (2009) Electronic structure and optical transitions in Sn and SnGe quantum dots in a Si matrix. Microelectronics Journal, 40 (3). pp. 483-485. ISSN 0026-2692

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Self-assembled quantum dots in the Si–Ge–Sn system have attracted research attention as possible direct band gap materials, compatible with Si-based technology, with potential applications in optoelectronics. In this work, the electronic structure near the G-point and the interband optical matrix elements of strained Sn and SnGe quantum dots in a Si matrix are calculated using the eight-band k.p method, and the competing L-valley conduction band states were found by the effective mass method. The strain distribution in the dots was found within the continuum mechanical model. The bulk bandstructure parameters, required for the k.p or effective mass calculation for Sn were extracted by fitting to the energy band structure calculated by the non-local empirical pseudopotential method (EPM). The calculations show that the self-assembled Sn/Si dots, with sizes between 4 and 12 nm, have indirect interband transition energies (from the size-quantized valence band states at G to the conduction band states at L) between 0.8 and 0.4 eV, and direct interband transitions between 2.5 and 2.0 eV, which agrees very well with experimental results. Similar good agreement with experiment was also found for the recently grown SnGe dots on Si substrate, covered by SiO2. However, neither of these is predicted to be direct band gap materials, in contrast to some earlier expectations.

Item Type: Article
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Institute of Microwaves and Photonics (Leeds)
Depositing User: Repository Officer
Date Deposited: 10 Mar 2009 16:18
Last Modified: 06 Jun 2014 06:48
Published Version: http://dx.doi.org/10.1016/j.mejo.2008.06.077
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.mejo.2008.06.077
URI: http://eprints.whiterose.ac.uk/id/eprint/7939

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