Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
the second Si cap layer was grown at 700 ◦ C, as shown in Fig. 5.20(c).
Figure 5.20: The layer scheme of the two conrmation samples and their corresponding
cross-section TEM images. (a) The layer scheme of sample one with one-step capping
at 700 ◦ C. (b) Dark eld cross-section TEM image of sample one showing no QDs
formation after buer interface (red dashed line). (c) The layer scheme of sample two
with two InAs QDs layers, above the second layer two steps Si over growth were used at
400 ◦ C and 700 ◦ C. (d) Dark eld cross-section TEM image of sample two shows QDs
formation with two-steps capping in second QDs layer marked with white dashed line
and no QDs formation after buer interface at rst QDs layer (red dashed line) with
one-step capping (sample one). (TEM performed@PDI-Berlin).
The dark eld cross section TEM image of the rst sample Fig. 5.20(b) con-
rmed that there are no QDs formed after the buer layer growth and even
during the whole deposition process of the 130 nm thick Si cap layer, which is
consistent with our expectation. The same observation was proved again in the
dark eld cross-section TEM image of the second sample before the second QDs
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