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

More documents

Recommendations

Info

36 CHAPTER 3. METHODS OF INVESTIGATION Figure 3.4: For miscut Si(001) substrates the average orientation usually deviates from the specific (001)-crystal direction. a) Short terrace segments are hard to resolve by AFM which impedes accounting for the tilted surface via the miscut angle. b) The step-bunching morphology exhibits flat and wide (001)-oriented terraces which enables tilt-correction. � Source: AFM tilt-correction.jpg Although there are some benefits of image-processing software, it may not be used care- lessly, as it could lead to data misrepresentation. Careless flattening could change structure curvature or could make features even disappear, as well as irresponsible filtering could add artificial structures to the image. Usually a tilted surface cannot be identified as such directly from the height-scale AFM-data. Just with additional structure-related knowledge about the orientation of intrinsic morphological features, e.g. facet angles, the correct surface orientation can be deduced which provides thereafter angle measurements with meaningful values (see Fig. 3.4). [74] 3.3.4 Data Types and Data Representation In this work a Digital Instruments Veeco Dimension 3100 AFM with Nanoscope IV controller [83] was employed with Olympus TESP tips [84] in the ”tapping” mode to map highly resolved surface images. There are two signals or data types that are collected by the AFM-system which are exploited for the thesis at hand. The ”height” data, which give directly the topographic information of the surface morphology, correspond to the change in piezo height (z-direction) needed to keep the amplitude of the cantilever vibration constant. Thus for the acquisition of the ”height” data the feedback gains must be high enough, so that the sample surface can be tracked and the change in oscillation amplitude of the tip is minimized. The ”amplitude” data measure the change in amplitude relative to the amplitude setpoint. Using high feedback gains for collecting ”amplitude” data gives the derivative of the topographic height in scan-direction. Hence the ”amplitude” data are often also referred to
3.3. ATOMIC FORCE MICROSCOPY (AFM) 37 Figure 3.5: Schematic illustration of the evaluation of AFM data for the surfaceorientation-map (SOM). a) 3D-model of a faceted wire profile with surface normal vectors (”1”, ”2”, ”3”). For each surface point (black spot) the normal orientation [hkl] (here shown for ”2”) is calculated with the nearest-neighbor points (red spots) to determine the local plane (rectangle colored orange). b) The intersection points of the local normal vectors and a half-sphere seen from top as projection gives a 2D-plot in polar coordinates (ρ, φ). c) Whereas ρ indicates the angle between the respective local surface normal [hkl] and the (001)-surface (growth direction), φ denotes the in-plane azimuthal angle of [hkl] with respect to [100] (seldom [110]). The intensity at each point (ρ, φ) in the surface orientation histogram is a measure of the abundance of a respective surface orientation. Marker circles which correspond to specific surface angles are introduced as guidance for the characteristic facets in the SiGe-system. � Source: AFM SOM schematic.jpg as ”derivative” data or data acquired in ”derivative” mode. The ”amplitude” mode provides a sensitive edge-detection technique which reveals facets with a better signal-to-noise ratio. [83] The topographic AFM data (”height” mode) can be also utilized to calculate special data representation plots to point out special morphological features or arrangements. Espe- cially useful to evaluate faceted morphologies are the surface-angle-plots (SAP) and surfaceorientation-maps (SOM). These are introduced to visualize the local surface inclination in each AFM data point itself or to depict a histogram of the involved surface orientations, respectively. Fig. 3.5 demonstrates the evaluation of AFM ”height” data for the surface-
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 and 16: 1.1. STRUCTURAL PROPERTIES 5 Figure
Page 17 and 18: 1.2. VICINAL SI(001) 7 Vicinal subs
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 45: 3.3. ATOMIC FORCE MICROSCOPY (AFM)
Page 49 and 50: 3.3. ATOMIC FORCE MICROSCOPY (AFM)
Page 51: Part II Main Research 41
Page 54 and 55: 44 CHAPTER 4. SELF-ORGANIZED GROWTH
Page 96 and 97:
86 CHAPTER 6. P-MODULATION DOPING A
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
100 CHAPTER 6. P-MODULATION DOPING
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 125 and 126:
Chapter 7 Transient-Enhanced Si Dif
Page 127 and 128:
7.3. EXPERIMENTAL RESULTS 117 > 100
Page 129 and 130:
7.3. EXPERIMENTAL RESULTS 119 Figur
Page 131 and 132:
7.4. DETAILED CHARACTERIZATION AND
Page 133 and 134:
7.4. DETAILED CHARACTERIZATION AND
Page 135 and 136:
Chapter 8 Germanium Source Reconstr
Page 137 and 138:
Figure 8.2: Elevated front-view of
Page 139 and 140:
water lines. Figure 8.4: Photograph
Page 141 and 142:
Figure 8.7: Part 2 of final constru
Page 143 and 144:
Appendix A Calibration and Characte
Page 145 and 146:
A.1. CALIBRATIONS 135 Figure A.1: X
Page 147 and 148:
A.1. CALIBRATIONS 137 Figure A.3: N
Page 149 and 150:
A.2. PHOTOLUMINESCENCE 139 Sample 1
Page 151 and 152:
A.2. PHOTOLUMINESCENCE 141 Figure A
Page 153 and 154:
A.2. PHOTOLUMINESCENCE 143 Figure A
Page 155 and 156:
Appendix B General Physical Data B.
Page 157 and 158:
Bibliography [1] Herbert Lichtenber
Page 159 and 160:
BIBLIOGRAPHY 149 [42] M. B. Prince,
Page 161 and 162:
BIBLIOGRAPHY 151 [85] J. Zhu, K. Br
Page 163 and 164:
BIBLIOGRAPHY 153 [130] C. S. Peng,
Page 165 and 166:
BIBLIOGRAPHY 155 [174] G. Medeiros-
Page 167 and 168:
BIBLIOGRAPHY 157 [214] G. Bastard,
Page 169 and 170:
Postface Curriculum Vitae ⋄ ∗ 1
Page 171 and 172:
POSTFACE 161 � D. Gruber, D. Pach
Page 173:
POSTFACE 163 Abbreviations AFM Atom
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?