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 the second Si cap layer was grown at 700 ◦ C, as shown in Fig. 5.20(c). Figure 5.20: The layer scheme of the two conrmation samples and their corresponding cross-section TEM images. (a) The layer scheme of sample one with one-step capping at 700 ◦ C. (b) Dark eld cross-section TEM image of sample one showing no QDs formation after buer interface (red dashed line). (c) The layer scheme of sample two with two InAs QDs layers, above the second layer two steps Si over growth were used at 400 ◦ C and 700 ◦ C. (d) Dark eld cross-section TEM image of sample two shows QDs formation with two-steps capping in second QDs layer marked with white dashed line and no QDs formation after buer interface at rst QDs layer (red dashed line) with one-step capping (sample one). (TEM performed@PDI-Berlin). The dark eld cross section TEM image of the rst sample Fig. 5.20(b) conrmed that there are no QDs formed after the buer layer growth and even during the whole deposition process of the 130 nm thick Si cap layer, which is consistent with our expectation. The same observation was proved again in the dark eld cross-section TEM image of the second sample before the second QDs 86
5.4 Self-Assembled InAs QDs Embedded in Si Matrix layer growth Fig. 5.20(d), which is highlighted by dashed red line. On the other hand, the white dashed line in Fig. 5.20(d) shows up a very clear QDs formation (second QDs layer) after two steps of Si overgrowth, which represents a second strong evidence of the proposed model and growth scenario. 5.4.4 Growth Model of InAs QDs embedded in Si Matrix From the last study all the previous ndings related to Si surface reconstruction and evolution are conrmed now. One can conclude a growth model (Fig. 5.21) that summarizes all the growth steps of InAs QDs embedded in Si matrix. Figure 5.21: Schematic diagram of the growth model of InAs QDs embedded in Si matrix at dierent growth stages. Fig. 5.21 shows that the InAs QDs with half lens shape are forming at growth temperature of 400 ◦ C. The formation of highly strained QDs together with surface energy balance prevents the direct overgrowth of Si at low temperature like 400 ◦ C and Si growth only happens on the surrounding areas around InAs QDs forming pits or voids. An interesting Si surface reconstruction with circular-voids 87
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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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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 50 and 51: 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
Page 142 and 143: Conclusions substrates, respectivel
Page 144 and 145: REFERENCES [8] J. M. Gerard, O. Cab
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Page 148 and 149: 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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