Suppression of Ostwald ripening in In0.5Ga0.5As quantum dots on a vicinal (100) substrate

Abstract

A comparative study of the morphology of self-assembled In0.5Ga0.5As quantum dots grown by atmospheric pressure metal-organic chemical vapor deposition on the exact (100) and 2 degrees-off (100) GaAs substrates as a function of growth interruption time (0-1200 sec) is presented. The dots are randomly distributed on the exact (100) substrate, whereas the dots on the 2 degrees-off (100) substrate are aligned along multiatomic steps. As the interruption time t is increased, the density of dots on the exact (100) substrate decreases and their average volume progressively increases with similar to t(3/4) dependence, indicating a regular Ostwald-ripening process. By contrast, the average volume of dots on the 2 degrees-off (100) substrate saturates for interruption times over 200 sec and shows obvious suppression of ripening. In particular, the size of dots on the 2 degrees-off (100) substrate is limited within the atomic terrace width (similar to 55 nm). These results demonstrate that the density and size of dots could be controlled by interruption time and substrate miscut angle. [S0163-1829(98)04416-6].