Si nanocrystals in sic matrix and infrared spectroscopy of in a dielecric matrix

Gencer İmer, Arife
This study focuses on various aspects of nanocrystals embedded in a dielectric matrix. In the first part of this work, a new approach with the use of Fourier Transform Infrared spectroscopy (FTIR) in the nanocrystal analysis was developed and presented. Si and Ge nanocrystals embedded in SiO2 matrix were mainly studied. This new approach is based on the analysis of structural variations of SiO2 matrix during the formation of semiconductor nanocrystlas. It is shown that the chemical and structural variations of the host matrix are directly related to the precipitation of nanocrystals in it. This correlation provides valuable information about the presences of nanocrystals in the matrix. In the second part of this work, fabrication of SiC films with and without Si nanocrystals inclusions was studied. With this aim, stoichiometric SiC and Si rich SiC thin films were fabricated by using magnetron co-sputtering and Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques. For SiC films, the structural and optical analyses were performed. For Si rich SiC films, the formation conditions of Si nanocrystals were investigated. Post annealing studies were carried out to track the evolution of the SiC matrix and formation of Si nanocrystals at different temperatures. Chemical and structural properties of the SiC host matrix were investigated with FTIR spectroscopy. Optimum conditions for the fabrication of stoichiometric SiC layers were determined. The crystallography of the nanocrystals was investigated by X-Ray Diffraction (XRD). The variation of the atomic concentrations and bond formations were investigated with X-Ray Photoelectron Spectroscopy (XPS). Raman spectroscopy and Transmission Electron Microscopy (TEM) were used to verify the formation of Si nanocrystals. We have shown that both single and multilayer Si nanocrystals can be fabricated in the amorphous SiC matrix for applications such as light emitting diodes and solar cells.


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Şimşek, Yusuf; Esendemir, Akif; Department of Physics (2008)
The aim of this study is to develop a software which calculates reflection, transmission and absorption of multilayered thin films by using complex indices of refraction, as a function of both wavelength and thickness. For these calculations matrix methods will be considered and this software is programmed with the matrix method. Outputs of the program will be compared with the theoretical and experimental results studied in the scientific papers.
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In this study some of the spatial and spatio-temporal methods for the solution of the inverse problem of electrocardiography (ECG) are compared with each other. Comparisons are also made for the cases with geometric errors, where the location of the heart is shifted for 10mm and the size of the heart is reduced by 5%. The compared methods are the Kalman filter and Bayesian maximum a posteriori estimation (MAP). Two different Bayesian-MAP algorithms are used. While one uses only spatial information the other...
Pulse phase resolved x-ray spectroscopy of four accretion powered millisecond pulsars
Çolak, Sıdıka Merve; Baykal, Altan; Department of Physics (2014)
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Direct identification and expansion of damping matrix for experimental-analytical hybrid modeling
Özgen, Gökhan Osman (Elsevier BV, 2007-11-20)
The theory of direct experimental identification of damping matrix based on the dynamic stiffness matrix (DSM) method is further developed in this work. Based on the relationship between the DSMs of the smaller experimental model and larger analytical model, the mathematical relationship between the damping matrices of the two models is established. Examining the relationship, two methods are developed that can be used to expand the experimental damping matrix to the size of the analytical model. Validity o...
Citation Formats
A. Gencer İmer, “Si nanocrystals in sic matrix and infrared spectroscopy of in a dielecric matrix,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.