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

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
growth temperature and V/III ratio were studied morphology wise. However, under
optimized growth conditions the In 0.5 Ga 0.5 As QDs were overgrown with Si cap
layer at the same QDs growth temperature for further optical characterization.
f(x) = a(x) − a sub
a sub
(5.13)
a(x) = a GaAs + (a InAs − a GaAs )x (5.14)
a(x = 0.5) = 5.65325 + (6.0583 − 5.65325)0.5 = 5.8557 A ◦ (5.15)
As a rst growth parameter the growth temperature was varied. Four MLs of
In 0.5 Ga 0.5 As with a V/III ratio of 20 and a growth rate of 220 nm/h were grown
on n-type Si (100) substrate. The AFM images in Fig. 5.28 shows a clear QD size
and density dependence on the growth temperature in the range of (470−530) ◦ C.
Figure 5.28:
(1 × 1 µm 2 ) AFM images of a sample grown with 4 MLs In 0.5 Ga 0.5 As
QDs and a V/III ratio of 20 on 50 nm Si buer grown on exactly oriented n-type Si
(100) substrate with dierent growth temperature. (a) 470 ◦ C. (b) 500 ◦ C. (c) 530 ◦ C.
A very homogeneous size distribution with diameter (D) in the range of 15 - 25
nm, hight (H) ranging from 3 - 7 nm as well as height QDs density of ∼ 10 11 cm −2
was observed at a growth temperature of 500 ◦ C (Fig. 5.28(b)). It has been found
that the amount of In 0.5 Ga 0.5 has a stronger impact on QDs density and size
distribution as shown in Fig. 5.29. Fig. 5.29(a) with 1 ML In 0.5 Ga 0.5 As coverage
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