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Examines the surface morphology of indium films by scanning tunneling microscopy. Vertical surface displacement on the films; Atomistic simulations within a valence force field model; Misfit dislocation network at the semicoherent interface.

Interfacial stability and the morphology of the epitaxial film surface have been studied in InAs/GaAs(111)A heteroepitaxy based on atomistic simulations and scanning tunneling microscopy. Effects of buffer layer thickness were examined by analyzing two heteroepitaxial systems consisting of thin and thick GaAs buffer layers. In both cases, one monolayer of In[sub 0.50]Ga[sub 0.50]As is grown initially on the buffer layer prior to InAs growth. Our results indicate that film compositional grading and the resulting segregation of In atoms at defects in the semicoherent interface can be used effectively in conjunction with the mechanical compliance of thin buffer layers to delay the completion of the coherent-to-semicoherent interfacial transition. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The mechanical behavior of thin buffer layers for InAs/GaAs(111)A heteroepitaxy has been investigated by x-ray diffraction (XRD). XRD θ-2θ spectra are presented for the (220) reflection for two monolayers (MLs) of InAs deposited on GaAs buffer layers of both 20 ML and 150 nm (≅ 460 ML) in thickness. For the thicker buffer layer, the XRD spectrum exhibits a single, symmetric peak at a reflected angle corresponding to the bulk GaAs lattice parameter, while for the thinner one it exhibits asymmetry around the GaAs substrate reflection with the spectrum tailing to lower angle. This indicates that the thin buffer layer possesses a distribution of interlayer distances in the [220] direction that are larger than that of the GaAs substrate. The XRD data agree very well with theoretical calculations in which the thin GaAs buffer layer is modeled as unconstrained at its base. Our results provide direct evidence that thin GaAs buffer layers behave mechanically similarly to compliant substrates. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]