Self-assembled C-induced Ge dots are islands which are not formed by the Stranski-Krastanov mode of growth. They are formed by a three-dimensional mode originating from the undulating strain fields of the C alloyed Si (100) surface. This opens additional possibilities to control the size and the shape of these dots by modifying the strain fields of the C-alloyed Si surface. Here, we show that the amount of C deposited prior to the growth of the Ge islands strongly effects the diameter and height of the dots. Increasing the C coverage to 0.3 monolayer leads to the formation of comparably compact islands. Consequently, the photoluminescence of the dots is shifted to lower energies compared to dots grown with lower C coverages.
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