Smakman, E. P. and Garleff, J. K. and Young, R. J. and Hayne, M. and Rambabu, P. and Koenraad, P. M. (2012) GaSb/GaAs quantum dot formation and demolition studied with cross-sectional scanning tunneling microscopy. Applied Physics Letters, 100 (14): 142116. -. ISSN 0003-6951
Abstract
We present a cross-sectional scanning tunneling microscopy study of GaSb/GaAs quantum dots grown by molecular beam epitaxy. Various nanostructures are observed as a function of the growth parameters. During growth, relaxation of the high local strain fields of the nanostructures plays an important role in their formation. Pyramidal dots with a high Sb content are often accompanied by threading dislocations above them. GaSb ring formation is favored by the use of a thin GaAs first cap layer and a high growth temperature of the second cap layer. At these capping conditions, strain-driven Sb diffusion combined with As/Sb exchange and Sb segregation remove the center of a nanostructure, creating a ring. Clusters of GaSb without a well defined morphology also appear regularly, often with a highly inhomogeneous structure which is sometimes divided up in fragments. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3701614]