Size control of carbon-induced Ge quantum dots

Self-assembled C-induced Ge dots are islands which are not formed by the St ranski-Krastanov mode of growth. They are formed by a three-dimensional mod e originating from the undulating strain fields of the C alloyed Si (100) s urface. This opens additional possibilities to control the size and the sha pe 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 G e islands strongly effects the diameter and height of the dots. Increasing the C coverage to 0.3 monolayer leads to the formation of comparably compac t islands. Consequently, the photoluminescence of the dots is shifted to lo wer energies compared to dots grown with lower C coverages. (C) 2000 Americ an Institute of Physics. [S0003-6951(00)02946-6].