Open Access Nano Express

Structural evolution of GeMn/Ge superlattices grown by molecular beam epitaxy under different growth conditions

Ya Wang1, Zhiming Liao1, Hongyi Xu1, Faxian Xiu2, Xufeng Kou4, Yong Wang13*, Kang L Wang4, John Drennan5 and Jin Zou15*

Author Affiliations

1 Division of Materials, The University of Queensland, Brisbane, QLD 4072, Australia

2 Department of Electrical and Computer Engineering, Iowa State University, Ames, IA, 50011, USA

3 Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China

4 Department of Electrical Engineering, University of California at Los Angeles, CA, 90095, USA

5 Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072, Australia

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Nanoscale Research Letters 2011, 6:624  doi:10.1186/1556-276X-6-624

Published: 12 December 2011

Abstract

GeMn/Ge epitaxial 'superlattices' grown by molecular beam epitaxy with different growth conditions have been systematically investigated by transmission electron microscopy. It is revealed that periodic arrays of GeMn nanodots can be formed on Ge and GaAs substrates at low temperature (approximately 70°C) due to the matched lattice constants of Ge (5.656 Å) and GaAs (5.653 Å), while a periodic Ge/GeMn superlattice grown on Si showed disordered GeMn nanodots with a large amount of stacking faults, which can be explained by the fact that Ge and Si have a large lattice mismatch. Moreover, by varying growth conditions, the GeMn/Ge superlattices can be manipulated from having disordered GeMn nanodots to ordered coherent nanodots and then to ordered nanocolumns.

PACS: 75.50.Pp; 61.72.-y; 66.30.Pa; 68.37.L.

Keywords:
ferromagnetic semiconductor; transmission electron microscopy; magnetic precipitation; molecular beam epitaxy