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

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
Sample Number
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Growth Conditions
50 nm Si at 700 ◦ C + PGA at 800 ◦ C for 10 min. + 2 ML
InAs QDs at 400 ◦ C
50 nm Si at 700 ◦ C + PGA at 800 ◦ C for 10 min. + 2 ML
InAs QDs at 400 ◦ C + 10 nm Si at 400 ◦ C
50 nm Si at 700 ◦ C + PGA at 800 ◦ C for 10 min. + 2 ML
InAs QDs at 400 ◦ C + 10 nm Si at 400 ◦ C+ PGA at 700 ◦ C
for 5 min.
50 nm Si at 700 ◦ C + PGA at 800 ◦ C for 10 min. + 2 ML
InAs QDs at 400 ◦ C + 10 nm Si at 400 ◦ C+ PGA at 700 ◦ C
for 5 min.+ 40 nm Si at 700 ◦ C
50 nm Si at 700 ◦ C + PGA at 800 ◦ C for 10 min. + 2 ML
InAs QDs at 400 ◦ C + 10 nm Si at 400 ◦ C+ PGA at 700 ◦ C
for 5 min.+ 40 nm Si at 700 ◦ C+ PGA at 800 ◦ C for 5 min.
Table 5.2:
capping investigations.
The samples series with detailed growth conditions for the PGA and Si
5.4.3 The Inuence of Post-Growth Annealing and Si Capping
In order to study the eect of post growth annealing (PGA) and Si overgrowth
(capping) on the grown structure, another series of samples were prepared for
this study. Table 5.2 summarized the growth conditions of the grown samples
investigated in this section. An interesting Si surface reconstruction and evolution
around and over the InAs QDs were observed. In addition, InAs QDs experienced
a shape transition from at and pyramidal shape to spherical and multi-faceted
QDs shape after PGA and further Si capping. These series of samples were grown
on exactly oriented Si (100) n-doped substrates. After our standard in-situ and
ex-situ surface treatment, a 50 nm silicon buer was grown at 700 ◦ C followed by
10 minutes PGA at 800 ◦ C. Afterwards, the substrate temperature was reduced
to 400 ◦ C for further 2 MLs deposition of InAs QDs.
The rst sample was unloaded directly after 2 MLs InAs QDs growth for
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