Chaldyshev, V. V., Faleev, N. N., Bert, N. A., Musikhin, Y. G., Kunitsyn, A. E., Preobrazhenskii, V. V., Putyato, M. A., Semyagin, B. R. and Werner, P.
Journal of Crystal Growth 202, pp 260-262 (1999) The InAs/GaAs superlattices with up to 30 periods were grown by molecular-beam epitaxy at 200 degrees C. The thickness of the GaAs layers was varied from 20 to 60 nm. The nominal thick ness of the InAs layers was either 1 or 0.5 monolayers. High-resolution transmission electron microscopy study revealed indium containing layer to be as thick as 4 monolayer in both cases. This was attributed to the roughness of the growth surface at the low substrate temperature. The concentration of As antisite defects in the as-grown samples was evaluated as (0.5-2) x 10(20) cm(-3). In spite of such a high concentration of point defects, the X-ray rocking curves were found to be very close to theoretical ones with a large number of interference patterns originated from periodical structure. Upon annealing the excess arsenic precipitated at the InAs delta-layers and in between them. Appropriate annealing conditions were found which allow us to dissolve the clusters in the GaAs spacers and accumulate the majority of clusters in two-dimensional sheets. As a result, artificially ordered superlattices of As cluster sheets were produced. (C) 1999 Elsevier Science B.V. All rights reserved. [References: 9]
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