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 = 6 kV, growth temperature = 700 ◦ C for both samples and only the time for each sample was varied. Sample No. Sample 1 Sample 2 Growth parameter Growth rate Thickness Growth rate Thickness [nm/h] [nm] [nm/h] [nm] Deposition controller 140 100 135 50 Prolometer 310 220 290 115 Table 5.1: Calibration of electron beam evaporator (EBE) silicon cell using two different samples. Table 5.6 shows the calibration parameters of the grown samples. The average tooling factor according to Eq. 5.6 was found equal to 225. Figure 5.4: 115 nm silicon buer layer grown on n-type (100) silicon substrate 0 ◦ o cut. (a) AFM image (1×1 µm 2 ) with RMS = 0.12 nm, and (b) HR-XRD measurement with FWHM values before (red curve) and after Si buer growth (black curve). The corresponding growth rate for I emission = 72 mA and V = 6 kV was approximated to 300 nm/h or 5 nm/min. Fig. 5.4 shows the AFM image and HR-XRD measurement of the sample with a 115 nm thick silicon buer layer. The root mean square (RMS) value of the surface roughness of 0.12 nm conrms 70
5.3 Results and Discussion the smoothness of the silicon buer layer, compared with an RMS value of 0.24 nm of the substrate before Si buer layer growth. On the other hand, the HR- XRD measurements show almost the same full width at half maximum (FWHM) value indicating together with TEM measurements (shown later) a very good crystalline quality of the Si buer layer. This in turns resulted in additional improvement in surface quality and creating a fresh Si surface ready for further III-V deposition. 5.3.3.2 InAs Coverage In this section the amount of deposited InAs material was varied in the range of 2 - 5 MLs. The rest of growth parameters are: V/III ratio of 25, growth temperature = 400 ◦ C, In growth rate = 108 nm/h (= 0.1 ML/s) on n-doped Si (100) were kept the same. Fig 5.5 shows clear size and density dependence on InAs coverage. The density and the size of InAs QDs increased with the increasing amount of InAs deposit in the range of 2 - 5 MLs from ∼ 10 10 cm −2 to ∼ 10 11 cm −2 and lateral sizes from 15 nm to 40 nm, respectively. Figure 5.5: (1 × 1 µm 2 ) AFM images of InAs QDs with dierent InAs coverage. (a) 2 MLs InAs, (b) 3 MLs InAs, and (c) 5 ML InAs. 5.3.3.3 Growth Temperature The growth parameters used in this section are: V/III ratio of 25, 2 MLs InAs coverage, In growth rate = 108 nm/h (= 0.1 ML/s) on n-doped Si (100) substrate 71
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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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Page 34 and 35: Theoretical Background of Semicondu
Page 36 and 37: Heteroepitaxial Growth of III-V Sem
Page 64 and 65: Experimental Growth and Characteriz
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Page 130 and 131: Optimization of MEE and MBE growth
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Optimization of MEE and MBE growth
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Conclusions substrates, respectivel
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REFERENCES [8] J. M. Gerard, O. Cab
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REFERENCES [29] http://www.wmi.badw
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REFERENCES [49] M. R. Brenner: GaP/
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REFERENCES [66] Y. Ishida, T. Takah
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REFERENCES [84] A. Garcia, C. M. Ma
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REFERENCES [100] M. Felici, P. Gall
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REFERENCES [116] H. Usui, H. Yasuda
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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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