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

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
On the other hand, RHEED elongated spots in semicircle were observed without
AH treatment only after a thermal desorption at much higher temperatures (e.g.,
900 ◦ C for 15 minutes as shown in Fig. 5.1(b). The resulting pattern showed
streaks forming a semicircle, which indicates a 2D crystalline surface.
Figure 5.1:
RHEED pattern during the thermal desorption surface treatment. (a)
The diusive pattern indicating an amorphous surface. (b) The pattern in the form
of spots describing semicircle indicates a single crystalline surface and was observed at
900 ◦ C. (c) RHEED pattern (streaks) resulting during the thermal desorption treatment
at 700 ◦ C after the hydrogen cleaning step at 500 ◦ C for 45 minutes with P H = 3×10 −7
Torr.
Hence, one can conclude that thermal desorption accompanied with hydrogen
treatment is the most ecient method to prepare a clean 2D crystalline surface,
which is in agreement with literature according to which hydrogen treatment is
ecient to remove carbon contamination from the surface [81, 82]. Due to the fact
that a long time high temperatures thermal desorption will destroy pre-patterned
surfaces, like nanoholes, an in-situ thermal cleaning process was developed with
a reduced thermal budget.
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