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

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Heteroepitaxial Growth of III-V Semiconductor on Silicon Substrates Figure 3.9: Suppression of anti-phase domains in InAs layer by featuring double atomic step reconstruction on Si (001) substrate surface. Figure modied according to reference [50]. toluminescence of GaAs/Ge system demonstrated a large decrease in minority carrier lifetime with a large increase in interface recombination rates in the samples containing the APD defects versus those without [49]. Generally, APDs are expected to introduce states within the energy gap and give rise to non-radiative recombination. They therefore degrade the eciencies of LEDs and cause excess leakage in p-n junctions. Avoiding the APDs defect is tricky and demands control of the substrate surface structure prior to III-V growth, but it has been accomplished in systems like GaAs/Ge [60, 57]. Early research into direct III-V/Si MBE integration focused on high indexed Si substrates with a surface atomic structure providing bonding sites for alternating group-III and V-atoms, creating an electrically neutral interface to help preventing the formation of APDs [61]. However, many other authors have investigated surface preparations recipes, and reported many nucleation conditions which can minimize or eliminate the formation of APDs for many III-V/IV systems like GaAs/Si, GaP/Si and GaAs/Ge [62, 49, 60]. Another method has been provided ecient APDs suppression [63], utilizes silicon substrates whose surfaces are polished such that the surface atomic plane is intentionally misoriented a few degrees toward an orthogonal [110] direction away from the (001) surface in order to induce a double atomic step reconstruction (DASR) as schematically shown in Fig. 3.9. In contrast to the irregular single 44
3.4 Challenges of Heteroepitaxial Growth of III-V on Silicon Figure 3.10: Self annihilation anti-phase domains on [011] plane in a (001) zinc blende semiconductor by the close proximity of bonding of two APD faces. Figure modied according to reference [31]. steps of nominally on-axis (001) Si surface, deliberately mis-orienting the substrate toward [110] direction introduces a regular array of single steps running the [110] direction. These regular array of single steps line up in a manner of proper atomic positions, with planar atomic growth occurring in the (001) direction, as illustrated in Fig. 3.9. However, as the o-cut angle φ is increased, the density of steps increases and the average terrace width w decreases according to Eq. 3.18. Where h is the height of the step. w = h tan −1 (φ) (3.18) At high temperatures and under ultra-high vacuum conditions, o-cut (001) surfaces are known to transform from their initial single-stepped two-domains conguration to a lower energy single-domain conguration of double steps reconstruction [64, 65]. Double steps surfaces preserve sublattice orientation between neighboring terraces, thereby facilitating APDs-free III-V epitaxial growth on silicon substrates. In the event that single-stepped two-domains surface is not achieved, substrate o-cut may also serve to limit the extent of APDs in zinc-blende crystal structures by self annihilation as a result of APD-APD interaction. Here, APDs annihilation occurs at the line of intersection of the two APD 45
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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
Page 8 and 9: (MEE = migration enhance epitaxy) u
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Page 12 and 13: CONTENTS 3.4.4 Planar Defects Assoc
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Page 16 and 17: Introduction thesis a detailed stud
Page 18 and 19: Introduction 1.1.2 Thesis Approach
Page 20 and 21: Introduction 1.2 Thesis Outline The
Page 22 and 23: Theoretical Background of Semicondu
Page 36 and 37: Heteroepitaxial Growth of III-V Sem
Page 64 and 65: Experimental Growth and Characteriz
Page 78 and 79: MBE Growth of Self-Assembled InAs a
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MBE Growth of Self-Assembled InAs a
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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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