Bimodal distribution of Ge islands on Si(001) grown by LPCVD

Hut- and dome-shaped islands have been observed during low-pressure vapour phase epitaxy (LPVPE) of Ge on Si(001) at 700 degrees C. The experiments sh ow an island height increase with increasing deposition time (total Ge-cove rage was kept constant). The shape transition from huts to domes, which tak es place after hut clusters have reached a baselength of 90 nm, indicates t hat huts are not a stable configuration. The two different island types are found to be the reason for the bimodal nature of the size distribution. Ph otoluminescence measurements show a linear correlation between hut cluster density and integrated photoluminescence intensity. (C) 2000 Elsevier Scien ce S.A. All rights reserved.