Figure 2
Schematic diagrams and CTEM micrographs of Ge nanocrystallites growth and migration into underneath buffer Si 3 N 4 . Ge nanocrystallite clusters migrate into the buffer Si3N4 underneath the original poly-Si0.85Ge0.15 pillar with coarsening and possible coalescence of these nanocrystallites after thermal annealing at 900°C for 30 min in an H2O ambient of the previously oxidized SiGe pillars over (a) 8-nm-thick, (b) 15-nm-thick, and (c) 22-nm-thick buffer Si3N4 layers. (d) Schematic diagram illustrating the mechanism of Si interstitials generated from the Si3N4 layers enhancing the coarsening and coalescence of Ge nanocrystallites when penetrating through thin and thick Si3N4 layers, respectively.