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Monitoring the kinetic evolution of self-assembled SiGe islands grown by Ge surface thermal diffusion from a local source

Vanacore, G. M. and Zani, M. and Bollani, M. and Bonera, E. and Nicotra, G. and Osmond, J. and Capellini, Giovanni and Isella, G. and Tagliaferri, A. (2014) Monitoring the kinetic evolution of self-assembled SiGe islands grown by Ge surface thermal diffusion from a local source. Nanotechnology, 25 (13). Art. No. 135606. ISSN 0957-4484.

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In this paper we experimentally study the growth of self-assembled SiGe islands formed on Si(001) by exploiting the thermally activated surface diffusion of Ge atoms from a local Ge source stripe in the temperature range 600–700 °C. This new growth strategy allows us to vary continuously the Ge coverage from 8 to 0 monolayers as the distance from the source increases, and thus enables the investigation of the island growth over a wide range of dynamical regimes at the same time, providing a unique birds eye view of the factors governing the growth process and the dominant mechanism for the mass collection by a critical nucleus. Our results give experimental evidence that the nucleation process evolves within a diffusion limited regime. At a given annealing temperature, we find that the nucleation density depends only on the kinetics of the Ge surface diffusion resulting in a universal scaling distribution depending only on the Ge coverage. An analytical model is able to reproduce quantitatively the trend of the island density. Following the nucleation, the growth process appears to be driven mainly by short-range interactions between an island and the atoms diffusing within its vicinities. The islands volume distribution is, in fact, well described in the whole range of parameters by the Mulheran's capture zone model. The complex growth mechanism leads to a strong intermixing of Si and Ge within the island volume. Our growth strategy allows us to directly investigate the correlation between the Si incorporation and the Ge coverage in the same experimental conditions: higher intermixing is found for lower Ge coverage. This confirms that, besides the Ge gathering from the surface, also the Si incorporation from the substrate is driven by the diffusion kinetics, thus imposing a strict constraint on the initial Ge coverage, its diffusion properties and the final island volume.

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Additional Information:© 2014 IOP Publishing. Received 10 October 2013, revised 30 December 2013; Accepted for publication 17 January 2014; Published 4 March 2014. This work was mainly supported by the CARIPLO Foundation through the EIDOS 2011-0382 project. A partial support by the Italian Ministry of Research MIUR through grant No. PRIN-20094W2LAY is also acknowledged.
Funding AgencyGrant Number
CARIPLO Foundation EIDOS Project2011-0382
Italian Ministry of Research MIURPRIN-20094W2LAY
Subject Keywords:SiGe islands; self-assembly; kinetics; surface diffusion; intermixing
Issue or Number:13
Classification Code:PACS: 66.30.Xj; 81.40.Ef; 81.05.Hd; 81.16.Dn; 68.35.B-; 68.35.Fx
Record Number:CaltechAUTHORS:20140418-103343929
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Official Citation:Monitoring the kinetic evolution of self-assembled SiGe islands grown by Ge surface thermal diffusion from a local source G M Vanacore et al 2014 Nanotechnology 25 135606
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45053
Deposited By: Jason Perez
Deposited On:18 Apr 2014 20:51
Last Modified:03 Oct 2019 06:25

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