Alignment of SiC quantum dots on silicon substrates

V. Cimalla 1A. A. Schmidt 1K. Zekentes 2Ch. Fvrster 1P. Weih 1Oliver Ambacher 1J. Pezoldt 1

1. Technische Universität Ilmenau, Zentrum für Micro- and Nanotechnologien, Ilmenau 98693, Germany
2. Microelectronics Research Group, University of Crete, Vassilika Vouton, P.O. Box 2208, Heraklion, Crete, Greece, Greece

Abstract

We demonstrate a linear alignment of self-assembled SiC quantum dots grown by molecular beam epitaxy on silicon substrates. The large lattice mismatch between Silicon and SiC of 20% stimulates a three-dimensional nucleation on the substrate. This spontaneous formation of islands is a powerful tool for the formation of quantum dots. Further more the average size of the nuclei can be easily controlled by the process conditions. However, the non-uniformities in the size and the distribution of the islands strongly limits the possible application e.g. in electronic devices. Thus, the control of the nucleation sites of SiC is a precondition for a lateral alignment of the SiC nuclei. In the technology of the formation of Ge clusters on silicon several ways to localize the nucleation sites are known, e.g., ordering on lithographically pre-patterned substrates , on dislocation networks , and along step arrays on vicinal substrates . Here we use the possibilities to form well ordered monoatomic steps, biatomic steps and step bands on (100) and (111) silicon, which offer the advantage that additional processing steps to define the alignment can be avoided. These terraces promote an alignment along their step edges. The arrangement was controlled by three key parameter with the following consequences: (i) the temperature and the flux control the nucleation density, (ii) the processing time defines the size, and (iii) the terrace width is adjusted close to the average distance of the nuclei. By atomic force microscopy we demonstrate the possibility to control an lateral ordering in linear chains and in dense dot arrays.

(i) G. Jin, J.L. Liu, S.G. Thomas et al, Appl. Phys. Lett. 75, 2752 (1999).
(ii) F. Leroy, J. Eymery, P. Gentile, and F. Fournel, Appl. Phys. Lett. 80, 3078 (2002).
(iii) K. Sakamoto, H. Matsuhata, M.O. Tanner et al, Thin Solid Films 321, 55 (1998).

 

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Presentation: oral at E-MRS Fall Meeting 2003, Symposium C, by J. Pezoldt
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-06-17 10:17
Revised:   2009-06-08 12:55