Structure of GaSb layers grown on (111) GaAs surfaces

Abstract

The structure of GaSb layers with thicknesses of 70Å, 160Å, and 1260Å grown on GaAs (111) substrates by metal-organic vapor phase epitaxy has been studied by high-resolution x-ray diffraction. The lattice mismatch between the layer and the substrate is large and most of the misfit strain is taken up by a regular network of dislocations localized at the interface between the GaSb and the GaAs. The spacing between the dislocations is about 49Å along the [1¯1¯2] direction. We observe that the layers have both the ABC… and ACB… face-centered-cubic (fcc) domains with a domain size of about 1500Å. The presence of approximately the same volume of both the domains in the overall layer suggests that the particular domain is chosen largely randomly and independent of the orientation of the substrate. In contrast, the results show that the structure of the GaAs substrate was a single fcc domain. The widths of the off-axis Bragg reflections along the [111] direction for the thinnest sample was within error the same as those for the (hhh) Bragg reflections showing that each fcc domain penetrated through the entire layer.

Direct Integration of GaSb with GaAs(111)A Using Interfacial Misfit Arrays

“…The extended appearance of this particular feature in the TEM image is likely due to through-thickness projection of the interface between regions. The presence of GaSb(111)­A regions with different orientations is reminiscent of features previously seen in InAs(111)­A epitaxial layers and consistent with reports of neighboring domains with ABCABC··· and ACBACB··· stacking in GaSb grown on GaAs(111)­A by MOCVD …”

“…Since the misfit dislocations can glide in this plane, mutual repulsive forces between them mean that the energy of the IMF array is minimized when they are spaced periodically. From careful analysis of HRTEM and IFFT images, we find the average separation between neighboring misfit dislocations is ∼46 Å, in good agreement with an existing high-resolution X-ray scattering study of this material system . On the (111) plane, a spacing of ∼46 Å corresponds to 13 GaSb lattice sites and 14 GaAs lattice sites, consistent with the number of lattice sites between misfits for IMFs in the GaSb/GaAs(001) system …”

Effects of Bi Irradiation on the Molecular Beam Epitaxy Growth of GaSb on Ge (111) Vicinal Substrates

“…Rotational twins are apt to be generated not only in the heteroepitaxial growth of III–V compound semiconductors on the (111) surface of group IV elemental semiconductors but also in the heteroepitaxial growth and even in homoepitaxial growth of III–V compound semiconductors on the (111) and surfaces of III–V compound semiconductors. The use of Bi as a surfactant is expected to be effective also for suppressing the generation of the rotational twins in the growth of III–V compound semiconductors on the (111) and surfaces of III–V compound semiconductors.…”