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

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Experimental Growth and Characterization Techniques Figure 4.4: Electron beam gun cell from MBE component (a) During operation, shows how the electron beam bends and focus on the target to start evaporation. (b) Electron beam gun with crucible for silicon target loading. (c) Silicon target before and after operation. silicon vapor, due to the high temperature melting point of silicon. It oers simple growth control due to the unity sticking coecient of elemental silicon, and a wide temperature range for growth. However, electron guns have some problems, such as poor growth rate control, electronic shutdown due to electrical discharge in e-beam source, and generation of surface defects due to charging of particles in the chamber. 4.3 Atomic Force Microscopy Atomic force microscopy is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer (atomic resolution), more than 1000 times better than the optical diraction limit. AFM provides a 3D prole of the surface on a nanoscale, by measuring forces between a sharp probe (
4.3 Atomic Force Microscopy and knowing the stiness of the cantilever. The probe is placed on the end of a cantilever (which one can think of as a spring). The amount of force between the probe and sample is dependent on the spring constant stiness of the cantilever and the distance between the probe and the sample surface. This force can be described using Hooke's Law described in Eq. 4.1. F = −kz (4.1) Where F is the force, k is the stiness of the lever, and z is the distance the lever is bent. However, the dominant interactions at short probe-sample distances in the AFM are Van der Waals (VdW) interactions. The AFM consists of a cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deection of the cantilever according to Hooke's law. Figure 4.5: Scheme of an atomic force microscope and the force-distance curve characteristic of the interaction between the tip and sample [71]. The motion of the probe across the surface is controlled using feedback loop and piezoelectronic scanner as it is shown in Fig. 4.5. If the electronic feedback is on, as the tip is raster-scanned across the surface, the piezo will adjust the tip sample separation so that a constant deection is maintained so the force is the same as its setpoint value. This operation is known as constant force 57
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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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Page 22 and 23: Theoretical Background of Semicondu
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Page 64 and 65: Experimental Growth and Characteriz
Page 78 and 79: MBE Growth of Self-Assembled InAs a
Page 118 and 119: MBE Growth of InAs and InGaAs Quant
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MBE Growth of InAs and InGaAs Quant
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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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