Effects of elastic field anisotropy on the heteroepitaxial growth of Ge quantum dots on vicinal Si surfaces

CFM Seminars

Speaker

L. Persichetti, Dipartimento di Fisica, Università di Roma "Tor Vergata", Via della Ricerca Scientifica, 1-00133 Roma, Italy

When

2012/11/19
13:00

Place

Auditorium of the Centro de Física de Materiales, Paseo Manuel de Lardizabal 5, Donostia-San Sebastián

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**_Effects of elastic field anisotropy on the heteroepitaxial growth of Ge quantum dots on vicinal Si surfaces_** ** __****__** _L. Persichetti 1 _* 1Dipartimento di Fisica, Università di Roma "Tor Vergata", Via della Ricerca Scientifica, 1-00133 Roma, Italy *Email: persichetti@roma2.infn.it Engineering the growth of strained epitaxial films is a fascinating perspective in modern nanoscale science. To this purpose, the challenge is to control the strain-relief mechanisms which play a key role in the growth of nanostructures. This can be done ‘‘artificially,’’ e.g., exploiting patterning surface features or multilayered structures. A conceptually different approach is the manipulation of heteroepitaxy through intrinsic properties of the substrate. To make this prospect feasible, one has to identify (1) distinct properties, which have impact on the growth process, and (2) a simple and reliable way of tuning them. In strained-layer epitaxy, the nature of the elastic field is a crucial parameter by definition. Since the elastic forces in solid materials act at the nanometer range, these interactions are particularly suited for bottom-up fabrication of semiconductor quantum dots. This talk will discuss the possibility to control the elastic environment of interacting Ge/Si islands by modulating the substrate orientation with miscut angle [1]. First, we will show that a fine shaping of Ge islands is possible by changing the miscut angle. This offers a direct way to easily alter the elastic- interaction potential among islands, which strongly depends on the detailed island’s shape [2-3]. Then, the breaking the isotropy of elastic interactions with miscut will be discussed as a potential way to force the growth of Ge on vicinal Si surfaces towards completely different pathways than on the flat substrate, as well as to determine the local spatial ordering of nanostructures [4-6]. Finally, we will demonstrate experimentally the structural and energetic changes induced by the epitaxial Ge deposition on the polar surface-energy diagram of Si near the (001) face and their implications on the Stranski- Krastanov growth nanofeatures [7]. [1] L. Persichetti, A. Capasso, A. Sgarlata, M. Fanfoni, N. Motta, and A. Balzarotti, in _Self-Assembly of Nanostructures_ , S. Bellucci, Ed. (Springer New York, New York, NY, 2012), vol. 12 of _Lecture Notes in Nanoscale Science and Technology_ , chap. 4, pp. 201-263. [2] L. Persichetti, A. Sgarlata, M. Fanfoni, and A. Balzarotti, Phys. Rev. Lett. **104** , 036104 (2010). [3] L. Persichetti, R. Menditto, A. Sgarlata, M. Fanfoni, and A. Balzarotti, Appl. Phys. Lett. **99** , 161907 (2011). [4] L. Persichetti, A. Sgarlata, M. Fanfoni, and A. Balzarotti, Phys. Rev. Lett. **106** , 055503 (2011). [5] L. Persichetti, A. Sgarlata, M. Fanfoni, and A. Balzarotti, Phys. Rev. B **82** , 121309(R) (2010). [6] L. Persichetti, A. Sgarlata, M. Fanfoni, and A. Balzarotti, Phys. Rev. B **81** , 113409 (2010). [7] L. Persichetti, A. Sgarlata, G. Mattoni, M. Fanfoni, A. Balzarotti, Phys. Rev. B **85** , 195314 (2012).