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

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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 96
5.5 Self-Assembled InGaAs QDs Embedded in Si Matrix Figure 5.29: (1 × 1 µm 2 ) AFM images of In 0.5 Ga 0.5 As QDs on buer Si grown on Si (100) with dierent In 0.5 Ga 0.5 A coverage. (a) 1 ML. (b) 2 MLs. (c) 4 MLs. (d) 8 MLs. shows a low density of ∼ 10 9 cm −2 and inhomogeneous QDs formation. However, an average dots size and density with a homogeneous size distribution found for In 0.5 Ga 0.5 As coverage of 2 MLs and 4 MLs are clearly shown in the AFM images Fig. 5.29(b,d). The inuence of the V/III ratio on In 0.5 Ga 0.5 As QDs structural properties was investigated by varying the V/III ratio from 10 to 30. A new series of samples with 4 MLs In 0.5 Ga 0.5 As and growth temperature of 500 ◦ C was grown on a Si buer but with dierent V/III ratios. Fig. 5.30 conrmed that there is a weak QDs size dependence on the V/III ratio in the range of 10 - 30. However, at the same time no strong In 0.5 Ga 0.5 As QDs density dependence on V/III was observed in the same range compared to the InAs QDs on Si. Fig. 5.30(b) with V/III ratio of 20 shows an average dots size, homogeneity 97
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Molecular Beam Epitaxial Growth of
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Gutachter (Supervisors): 1. Prof. D
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patterns indicating a 2D smooth sur
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(MEE = migration enhance epitaxy) u
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viii
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CONTENTS 3.4.4 Planar Defects Assoc
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CONTENTS xii
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Introduction thesis a detailed stud
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Introduction 1.1.2 Thesis Approach
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Introduction 1.2 Thesis Outline The
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Theoretical Background of Semicondu
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Heteroepitaxial Growth of III-V Sem
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Page 60 and 61: Heteroepitaxial Growth of III-V Sem
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Page 64 and 65: Experimental Growth and Characteriz
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Page 130 and 131: Optimization of MEE and MBE growth
Page 142 and 143: Conclusions substrates, respectivel
Page 144 and 145: REFERENCES [8] J. M. Gerard, O. Cab
Page 146 and 147: REFERENCES [29] http://www.wmi.badw
Page 148 and 149: REFERENCES [49] M. R. Brenner: GaP/
Page 150 and 151: REFERENCES [66] Y. Ishida, T. Takah
Page 152 and 153: REFERENCES [84] A. Garcia, C. M. Ma
Page 154 and 155: REFERENCES [100] M. Felici, P. Gall
Page 156 and 157: REFERENCES [116] H. Usui, H. Yasuda
Page 158 and 159: REFERENCES [133] Grassman, T. J. Br
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Conferences Contributions: Tariq Al
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Nomenclature
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REFERENCES symbol Descriptions γ f
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like to thank all member of the Ins
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REFERENCES Erklärung Hiermit versi
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Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA

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