Kinetic and Strain-Induced Self-Organization of SiGe ...

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6 CHAPTER 1. SILICON-GERMANIUM MATERIAL SYSTEM {hkl} : For planes of equivalent symmetry – such as {100} stands for (100), (010), (001), (100), (010), (001) in cubic symmetry. [hkl] : For a crystal direction, such as [100] for the x-axis-direction. Therefore the [hkl]- direction is perpendicular to the (hkl)-plane. 〈hkl〉 : As for the planes for a full set of equivalent directions – such as 〈100〉 stands for [100], [010], [001], [100], [010], [001]. In Fig. 1.3 [2] there are some important planes in cubic crystals depicted. In a Si-crystal the {111}-surface is the energetically favored surface-plane. 1.2 Vicinal Si(001) Generally Si-surfaces are never flat on a long scale. There are always steps even at nearly singular or low-index surfaces. These tilted surfaces are named ”vicinal” as the average surface orientation is usually close to the respective low-index surface and deviates only by a small miscut angles from the specific crystal-direction (Fig. 1.4). This is not always unwanted as a finite miscut provides several steps which enables ”step-flow” growth even at lower temperatures due to the large number of favored nucleation sites (”kinks”): the steps proceed by incorporation of adatoms at these kink sites along the step edges (red circle in Fig. 1.4) whereas on-terrace nucleation events are suppressed (blue circle in Fig. 1.4). Figure 1.4: Schematic visualization of vicinal Si(001) surface with a miscut angle between the nominal (001)-crystal direction and the average surface orientation. The high step-edge density offers favored nucleation sites in form of steps and ”kinks” on steps. � Source: SiGe miscut.jpg
1.2. VICINAL SI(001) 7 Vicinal substrates are in principal available with any miscut angle α and arbitrary azimuthal orientation φ. Commercial use is actually only made of Si(001) with a miscut of up to ± 4 ◦ . [8] 1.2.1 Step Structure Terraces on vicinal Si(001) which are separated by an odd number of mono-atomic steps show dimer rows which are oriented perpendicular to each other. These dimer rows are (2×1) and (1×2) reconstructed domains which are oriented along the [110] and [110] direction. This reconstruction reduces the number of dangling bonds and thus lowers the surface energy. There are two different types of step segments with mono-atomic height: the upper-terrace is either reconstructed with dimer rows parallel to the step edge (SA) or perpendicular to it (SB) [9]. Step edges with arbitrary direction according to their different azimuthal miscut orientations are assembled from such segments. For SB-steps two kinds have to be distin- guished depending on the registry of the step edge with the dimer row reconstruction on the lower-terrace. For rebonded SB step edges the number of dangling bonds is reduced which makes them energetically favorable compared to non-rebonded SB-steps. Double steps are observed primarily in form of DB-steps and here again mainly in the rebonded type [10, 11]. They separate terraces which expose dimer rows running perpendicular to the DB step edges. Figure 1.5: Schematic model of the most common step types on Si(001) showing SB and DB steps in their rebonded configuration [8]. � Source: SiGe vicinal-surface dimers.jpg
Page 1: J O H A N N E S K E P L E R U N I V
Page 4 and 5: ii PREFACE Kurzfassung Eine kinetis
Page 6 and 7: iv PREFACE
Page 8 and 9: vi CONTENTS 2.1.3 Growth-Modes . .
Page 10 and 11: viii CONTENTS B General Physical Da
Page 13 and 14: Chapter 1 Silicon-Germanium Materia
Page 15: 1.1. STRUCTURAL PROPERTIES 5 Figure
Page 19 and 20: 1.3. ELECTRONIC PROPERTIES 9 Monoat
Page 21 and 22: 1.3. ELECTRONIC PROPERTIES 11 Silic
Page 23 and 24: 1.4. SILICON GERMANIUM ALLOYS (SI1
Page 25 and 26: Chapter 2 Molecular Beam Epitaxy (M
Page 27 and 28: 2.1. MBE-GROWTH 17 hit the substrat
Page 29 and 30: 2.1. MBE-GROWTH 19 Figure 2.3: The
Page 31 and 32: 2.2. CLEANING PROCEDURE 21 rameter
Page 33 and 34: 2.2. CLEANING PROCEDURE 23 H2SO4 :
Page 35 and 36: 2.3. MBE-SYSTEM 25 Figure 2.7: All-
Page 37 and 38: 2.3. MBE-SYSTEM 27 Figure 2.9: Sche
Page 39 and 40: Chapter 3 Methods of Investigation
Page 41 and 42: 3.2. SCANNING ELECTRON MICROSCOPY (
Page 43 and 44: 3.3. ATOMIC FORCE MICROSCOPY (AFM)
Page 51: Part II Main Research 41
Page 54 and 55: 44 CHAPTER 4. SELF-ORGANIZED GROWTH
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56 CHAPTER 5. SELF-ORGANIZED GROWTH
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86 CHAPTER 6. P-MODULATION DOPING A
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100 CHAPTER 6. P-MODULATION DOPING
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Chapter 7 Transient-Enhanced Si Dif
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7.3. EXPERIMENTAL RESULTS 117 > 100
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7.3. EXPERIMENTAL RESULTS 119 Figur
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7.4. DETAILED CHARACTERIZATION AND
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7.4. DETAILED CHARACTERIZATION AND
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Chapter 8 Germanium Source Reconstr
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Figure 8.2: Elevated front-view of
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water lines. Figure 8.4: Photograph
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Figure 8.7: Part 2 of final constru
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Appendix A Calibration and Characte
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A.1. CALIBRATIONS 135 Figure A.1: X
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A.1. CALIBRATIONS 137 Figure A.3: N
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A.2. PHOTOLUMINESCENCE 139 Sample 1
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A.2. PHOTOLUMINESCENCE 141 Figure A
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A.2. PHOTOLUMINESCENCE 143 Figure A
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Appendix B General Physical Data B.
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Bibliography [1] Herbert Lichtenber
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BIBLIOGRAPHY 149 [42] M. B. Prince,
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BIBLIOGRAPHY 151 [85] J. Zhu, K. Br
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BIBLIOGRAPHY 153 [130] C. S. Peng,
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BIBLIOGRAPHY 155 [174] G. Medeiros-
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BIBLIOGRAPHY 157 [214] G. Bastard,
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Postface Curriculum Vitae ⋄ ∗ 1
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POSTFACE 161 � D. Gruber, D. Pach
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POSTFACE 163 Abbreviations AFM Atom
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Kinetic and Strain-Induced Self-Organization of SiGe ...

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