SUPPRESSION OF OSTWALD RIPENING IN IN0.5GA0.5AS QUANTUM DOTS ON A VICINAL (100) SUBSTRATE

A comparative study of the morphology of self-assembled In0.5Ga0.5As q uantum 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, wherea s the dots on the 2 degrees-off (100) substrate are aligned along mult iatomic 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 parti cular, the size of dots on the 2 degrees-off (100) substrate is limite d within the atomic terrace width (similar to 55 nm). These results de monstrate that the density and size of dots could be controlled by int erruption time and substrate miscut angle. [S0163-1829(98)04416-6].