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Real‐time tracking of the self‐assembled growth of a 3D Ge quantum dot lattice in an alumina matrix
Author(s) -
Shaji Ashin,
Micetic Maja,
Halahovets Yuriy,
Nadazdy Peter,
Matko Igor,
Jergel Matej,
Majkova Eva,
Siffalovic Peter
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576720007815
Subject(s) - grazing incidence small angle scattering , materials science , quantum dot , scattering , bilayer , tetragonal crystal system , crystallography , molecular physics , silicon , amorphous solid , condensed matter physics , optics , nanotechnology , optoelectronics , small angle neutron scattering , crystal structure , chemistry , physics , neutron scattering , biochemistry , membrane
A laboratory in situ grazing‐incidence small‐angle X‐ray scattering (GISAXS) tracking of the self‐assembled growth of a regular 3D Ge quantum dot (QD) structure in an amorphous Al 2 O 3 matrix during the ion beam sputter deposition of a periodic Ge/Al 2 O 3 multilayer on silicon is reported. A 573 K substrate temperature proved to be necessary to achieve the self‐assembly effect. Relying on a fast repeated acquisition of GISAXS patterns, the temporal evolution of the growing 3D Ge QD structure was analyzed bilayer by bilayer to determine its type, lateral and vertical correlation lengths, and inter‐QD distance. The QD structure was found to have body‐centered tetragonal lattice type with ABA stacking, with the lattice parameters refined by fitting the final GISAXS pattern relying on a paracrystal model. A single set of paracrystal parameters enables one to simulate the temporal evolution of the in situ GISAXS patterns throughout the deposition process, suggesting that the Ge QD self‐assembly is driven from the very beginning solely by the growing surface morphology. Ex situ GISAXS and X‐ray reflectivity measurements along with a cross‐section high‐resolution transmission electron microscopy analysis complete the study.