PHYS Ashutosh Rath - Homi Bhabha National Institute

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Experimental techniques 12 Layer plus Island growth mode(SK Growth) This growth mode is considered as intermediate between the FM and VW growth modes. After forming the first few monolayer, subsequent growth is unfavourable and islands are formed on the top of the intermediate layer. This type of growth is commonly known as Stranski-Krastanov(Fig. 2.1(b)). It happens if ∆γ ≤ 0 and the materials have large lattice mismatch and strain associated. This is due to the influences of the surface and the interfaces and also the film structure, determined by the initial condensation process. First it tries to form an wetting layer and after a critical thickness when no more strain can be accommodated, then only island forms. In SK growth, islanding happens to relieve the misfit strain. The clusters grow in size and density until the islands begin to merge in what is known as the coalescence phenomenon. Coalescence decreases the island density allowing further nucleation to occur. The strain-assisted self assembly in the Ge/Si(100) system is a popular example of this growth mode. Relaxation and Reconstruction: The atoms at solid surfaces have missing neighbors on one side. Driven by this asymmetry, the topmost atoms often assume a structure different from the bulk. They might form dimers or more complex structures to saturate dangling bonds. In the case of surface relaxation, the lateral or in-plane spacing of the surface atoms remains unchanged but the distance between the topmost atomic layers is altered. If the lateral distance of the atoms are changed, this is called the surface reconstruction. For example, semiconductor surfaces tend to exhibit surface reconstruction due to the directional character of the dangling bonds at the surface. Reconstruction can be readily detected by electron diffraction techniques, including low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED). A photograph of the MBE system used [78] for this thesis work is shown in Fig. 2.2. It is a custom-designed, compact MBE system along with the capability to transfer the MBE-grown samples to a UHV STM without breaking vacuum (Omicron, GmbH) (Fig. 2.2). It consists of a load-lock chamber and growth chamber which is connected to the STM chamber. Each chamber has an associated pumping system. The load-lock facilitates the introduction and removal of samples or wafers without
Experimental techniques 13 Figure 2.2: A custom-designed compact MBE system (MBE chamber diameter: 250 mm) and a UHV variable temperature scanning tunneling microscope (VTSTM) attached to it.
Page 1: DYNAMIC AND STATIC TEM STUDIES ON T
Page 4 and 5: Declaration I, Ashutosh Rath, hereb
Page 6 and 7: a special word of appreciation for
Page 8 and 9: List of Publications 1. 1‡ Epitax
Page 10 and 11: Muller,M. Schowalter, R.Imlau, A. R
Page 12 and 13: Synopsis The thesis work involves a
Page 14 and 15: gold nanostructures on Si (100) sur
Page 16 and 17: Au-Ge bilobed structures were forme
Page 18 and 19: Contents Statement By Author Declar
Page 20 and 21: 8 Summary 107 A Table to summarize
Page 22 and 23: 3.1 As deposited MBE sample showing
Page 24 and 25: 4.11 (a) SEM image taken at 54 o ti
Page 26 and 27: 6.7 Schematic diagram showing the A
Page 28 and 29: Introduction 2 giant magneto-resist
Page 30 and 31: Introduction 4 metals, in the case
Page 32 and 33: Introduction 6 and has been develop
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Page 46 and 47: Experimental techniques 20 spherica
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Page 64 and 65: Chapter 3 Temperature-dependent ele
Page 66 and 67: Temperature-dependent electron micr
Page 80 and 81: Chapter 4 Growth of Oriented Au Nan
Page 82 and 83: Growth of Oriented Au Nanostructure
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Growth of Oriented Au Nanostructure
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Structural modification of gold sil
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Nano scale phase separation in Au-G
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Gold assisted molecular beam epitax
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Summary 108 square /rectangular sha
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Summary 110 the annealed sample whi
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Bibliography [1] M. S. Gudiksen, L.
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BIBLIOGRAPHY 114 [32] Y. He, X. Yu
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BIBLIOGRAPHY 116 [67] M. Ohring Mat
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BIBLIOGRAPHY 118 [97] W. K. Chu, J.
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BIBLIOGRAPHY 120 [131] C. Suryanara
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BIBLIOGRAPHY 122 [167] C. R. Henry,
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BIBLIOGRAPHY 124 [201] E. Sutter an
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PHYS Ashutosh Rath - Homi Bhabha National Institute

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