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Controlled Ge quantum dots positioning with nano‐patterned Si(001) substrates
Author(s) -
Bavard A.,
Eymery J.,
Pascale A.,
Fournel F.
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200671533
Subject(s) - materials science , quantum dot , nanodot , trench , etching (microfabrication) , molecular beam epitaxy , relaxation (psychology) , nanotechnology , germanium , substrate (aquarium) , optoelectronics , epitaxy , silicon , layer (electronics) , psychology , social psychology , oceanography , geology
A square nanometric patterned substrate (period 20 nm) is obtained by direct twist bonding of two twin Si(001) surfaces, thinning and preferential chemical etching. Molecular beam epitaxy of Ge is carried out on a sample having heterogeneous trench depths to analyse islands positioning as a function of the surface morphology. Scanning electron microscopy observations show that small single dots per mesa or large dots covering several mesas can be observed. It highlights the influence of the mesa aspect ratio on the control of Ge islands self‐organization, and suggests the occurrence of an effective activation barrier depending on the surface profile. The position‐dependent energy stored in a dot for a given surface profile is estimated from a very simple model based on the balance between capillarity and elastic relaxation terms. By choosing a cycloid‐like profile, experimental observations can be explained without fitting parameters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)