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Strain Induced Compositional Modulations in AlGaAs Overlayers Induced by Lateral Surface Gratings
Published online by Cambridge University Press: 10 February 2011
Abstract
Strain and compositional modulation in AlxGa1−xAs layers grown by metalorganic vapour phase epitaxy (MOVPE) over a sinusoidally shaped GaAs (001) surface grating were studied by scanning electron microscopy (SEM), X-ray grazing-incidence diffraction (GID) and photoluminescence (PL). Two growth temperatures and two compositions were chosen to realize planar overlayers. By SEM a periodic reduction in Al-content was found at the valley positions of the GaAs grating. The appearance of such vertical quantum wells (VQWs) has been explained by the growth rate anisotropy between high-index and (001) planes and a curvature-induced capillarity flow of Ga. Estimated from PL energies a larger reduction of the Al-concentration in the VQW and also at the high-index sidewall facets was found than compared to predictions from the capillarity flow theory. Using depth-resolved GID we show that the formation of VQWs is accompanied by a periodic lateral strain field. Therefore we assume, that the formation of the VQWs is influenced by strain induced diffusion due to the interaction of opposite sidewall facets.
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- Copyright © Materials Research Society 2000
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