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Figure 4 | Nanoscale Research Letters

Figure 4

From: Excitation Intensity Driven PL Shifts of SiGe Islands on Patterned and Planar Si(001) Substrates: Evidence for Ge-rich Dots in Islands

Figure 4

a and b AFM micrographs of islands grown on planar Si(001) (5.5 ML at TGe = 700°C). The color scale represents the local surface slope with respect to (001). Every color corresponds to a certain facet of the SiGe domes (blue: {105}, yellow: {113}, red: {15 3 23}). cf: Calculated energy level scheme for islands grown on pit-patterned Si(001) substrates without regions of Ge enrichment (d, f) and islands grown on planar Si(001) substrates containing Ge-rich regions (c, e) as described in the text. The stronger Ge composition gradient of the islands grown on planar substrates compared to the ones grown on pit-patterned substrates [79] leads to a confining potential at the top of the island. The strong shift of the island signal on planar substrates at moderate P exc as observed in Figs. 1c, 2 and 3 is explained by the decreased density of states (indicated by the horizontal lines) in this confining potential

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