Determination of the roughness of heteroboundaries from photocurrent spectra of short-period AlAs/GaAs superlattices |
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Authors: | V L Al’perovich N T Moshegov V V Popov A S Terekhov V A Tkachenko A I Toropov A S Yaroshevich |
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Institution: | (1) Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia |
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Abstract: | Photocurrent spectroscopy is used to study the nature of the roughness of heteroboundaries in (AlAs)m/(GaAs)n short-period superlattices (m=3−5, n=10−13) grown by molecularbeam epitaxy. The formation of minibands broadens the optical spectra of superlattices in comparison
with isolated quantum wells; therefore to analyze the degree of perfection of the boundaries we used the decay of the minibands
into a series of discrete Wannier-Stark levels in an electric field parallel to the superlattice axis. Exciton lines were
observed in the photocurrent spectra in an electric field corresponding to direct and indirect (in space) transitions between
the Wannier-Stark levels. Comparison of experimental data with calculation indicates that even in the better structures, in
addition to monotonic variation of the thickness of the layers over area, roughnesses in the heteroboundaries one monolayer
in height are present with characteristic lateral dimension not exceeding 10 nm.
Fiz. Tverd. Tela (St. Petersburg) 39, 2085–2089 (November 1997) |
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