The growth of ridge structures on GaAs(OOl) patterned substrates has been investigated using Atomic Force Microscopy and Scanning Electron Microscopy. These techniques provide morphological and topographical information from which the kinetic processes of the adatom diffusion can be postulated.
The research is split into two main sections. The first concerns the growth of GaAs on GaAs (001) patterned substrates, involving variation of substrate temperature, the effective V/III ratio and deposition quantity. The effects of changing these growth parameters on the evolving facet morphology are investigated and direct comparison is made between growth on mesas with vertical and non-vertical sidewalls. In all cases {110} facets were formed and the degree of overgrowth of the ridge bases was found to be dependant on the growth conditions.
The second area concentrates on the growth of In As on GaAs(OOl) patterned substrates with vertical sidewalls. Here, the effect of differing growth conditions and initial mesa stripe width was studied, in particular with respect to the formation of quantum dots. Specific emphasis was placed on the alteration of the quantum dot number density and the implications in terms of the In adatom diffusion processes. It was observed that dot density and size varied considerably with respect to the initial mesa widths and the different growth conditions used. For all investigations the dot sizes were larger and the dot densities lower that those reported for InAs/GaAs growth on planar GaAs(OOl) substrates.