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Free keywords:
Molecular beam epitaxy; Scanning tunneling microscopy; Photoluminescence; Faceting; Gallium arsenide; Indium arsenide; High-index single crystal surfaces; Quantum dots; Scanning-Tunneling-Microscopy; Quantum dots; GaAs-surfaces; Shape; GaAs(001); Layer; Relaxation; Dependence; Morphology; Substrate
Abstract:
InAs was deposited onto nominal and vicinal (1.0 degrees-off-oriented) GaAs(2511)A surfaces by means of molecular beam epitaxy and studied by scanning tunneling microscopy and photoluminescence measurements. Both surfaces show step bunches along the [31 (1) over bar] direction which form fairly large (011) nano-facets. Large, inhomogeneously distributed InAs islands are formed on these nano-facets. The InAs islands exhibit a wide size distribution and vanishing photoluminescence intensity, both being characteristic for incoherent islands. The shape of the incoherent InAs islands is composed mainly of (111)A, (011), (001), and (317)A surfaces. During growth the latter undergoes a transition into the steeper (101) facet. The shape of the incoherent islands exhibits no symmetry in accordance with the missing of any symmetry at the GaAs(2511])A bulk-truncated substrate surface. On the flat terraces of the nominal GaAs(2511)A surface a second kind of QDs develops which are of the same shape but of a sharp size distribution. The photoluminescence intensity of the latter is quenched presumably by the coexistent incoherent InAs islands.
