Evolution of Ge/Si(100) islands: Island size and temperature dependence

Atomic force microscope (AFM) imaging and cross-sectional analysis were use d to document the shape evolution of Ge/Si(100) islands, grown by molecular beam epitaxy, as a function of growth conditions. Growth temperatures of 4 50, 550, 600, and 650 degrees C with Ge coverages between 3.5 and 14.0 mono layers (ML) were investigated for a deposition rate of 1.4 ML/min. Low cove rages produced small hut clusters which then evolved into dome clusters at higher coverages. These dome clusters eventually dislocated after further g rowth. Higher growth temperatures activated additional pathways for the Ge islands to relieve their strain such as Ge/Si intermixing and the formation of trenches around the islands. Our detailed AFM cross-sectional analysis indicated that dome clusters form several crystal facets in addition to tho se previously reported. (C) 2000 American Institute of Physics. [S0021-8979 (00)02905-4].