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

Optimization of MEE and MBE growth of GaP Buer on Silicon Substrate
for the Ga-initiated MEE growth recipe with RMS value of 0.51 nm which is in
agreement with the literatures [133, 49]. As a result the Ga-initiated growth with
the time sequence of 10 s Ga/ 4 s stop/10 s P 2 /60 s was chosen for all following
MEE runs. In the next subsections MEE growth mode was optimized for other
growth parameters like growth temperature and V/III ratio.
7.4.1 MEE-GaP Growth Temperature
Two samples with 10 nm nominal thickness were grown on p-type Si(100) substrates
with 5 ◦ o-cut after the surface treatment mentioned in Sec. 7.3 at dierent
growth temperatures.
Figure 7.2: (1×1 µm 2 ) AFM images of 10 nm GaP/Si at dierent growth temperatures
using Ga-initiated MEE-mode. (a) 350 ◦ C, RMS of 0.44 nm, (b) 400 ◦ C, RMS of 0.87
nm.
The inuence of the growth temperature was investigated using migration
enhanced epitaxy with Ga-initiated growth time sequence 10 s Ga/ 4 s stop/10
s P 2 /60 s, at two low temperatures in the range of 350 ◦ C to 400 ◦ C, with a
V/III ratio of 15 and a Ga growth rate of 100 nm/h. Fig. 7.2 shows that the best
value was obtained at a lower growth temperature of 350 ◦ C with an RMS value
of 0.44 nm compared to a rougher surface with RMS of 0.87 nm at higher growth
temperature of 400 ◦ C. Therefore, a growth temperature of 350 ◦ C was chosen as
an optimized temperature for the MEE growth step, which was later monitored
by RHEED.
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