Growth defects associated with MBE deposited GaAs layers

The morphological defects associated with MBE-grown GaAs layers have been investigated by SEM and EMPA analysis. A detailed investigation was carried out on the oval defects. EMPA analysis indicates that both the core and hillock regions have essentially the same composition. There is also a further evidence that the defects originate from regularly orientated polyhedral pits. Growth of ripple lines has been investigated in relation to the substrate orientation, growth rate and temperature. Their appearance is observed to be less pronounced for 2 degrees off (1 0 0) orientation of the substrate surface compared to that for a true (1 0 0) substrate. The effect is more significant for higher growth rate and lower substrate temperature. Finally, the other main growth-related defect, the whisker formation, is also considered. These are observed to be associated with the depletion of As-source material. (C) 1999 Elsevier Science Ltd. All rights reserved.