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

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
followed by dry and wet etching possibly cause serious crystalline damages and
some external chemical impurities [16].
5.4.1 Experimental Details
Self-assembled (SA) InAs quantum dots (QDs) were grown in silicon matrix with
dierent nominal thicknesses and on dierent substrate o-cuts. The rst series
of samples were grown on exactly oriented (100) n-type, phosphor doped silicon
substrate, while the second series were grown on 5 ◦ o-cut n-type (100) Si substrate.
After our standard ex-situ (2 min. BHF wet etching) and in-situ thermal
oxide desorption at 900 ◦ C for 15 minutes, silicon buer layer with a 50 nm thickness
was grown at 700 ◦ C followed by 10 minutes post growth annealing (PGA)
at 800 ◦ C, in order to improve the crystallinity of the silicon buer.
Figure 5.10:
Schematic diagram of X (1, 2 or 4) MLs InAs QDs embedded in Si
matrix. (a) Energy scheme of the structure. (b) Layer scheme of the grown structure.
The substrate temperature reduced after that to 400 ◦ C. At this temperature
two samples were grown with 1 ML, 2 MLs or 4 MLs InAs QDs (see Fig. 5.10).
At 400 ◦ C another 10 nm silicon cap layer was deposited to protect the InAs QDs
from desorption. The substrate temperature was ramped up to 700 ◦ C with a
76