Date of Award

1-1-2011

Degree Name

Doctor of Philosophy

Department

Physics

First Advisor

Dr. Asghar Kayani

Abstract

Deposition of Ultrananocrystalline Diamond (UNCD) films have been carried out and dielectric properties of nitrogen incorporated UNCD films were studied using spectroscopic ellipsometry (SE), UV/VIS spectroscopy, and reflectance spectroscopy. Dielectric functions of the films were correlated with their nanostructure, elemental concentration, and growth conditions. The films were grown in a 915 MHz microwave plasma chemical vapor deposition system with 0%, 10%, and 20% N2 gas diluted into Ar/CH4/H2 plasma. Samples were deposited on 6-inch Si substrates. For UV/VIS spectroscopy studies, samples were deposited on quartz substrates. The bonding structure was investigated by Raman spectroscopy and the surface morphology of the films was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Determination of the elemental composition of the deposited films was carried out by ion beam analysis (IBA) measurements. To obtain the precise concentration of carbon, hydrogen, nitrogen, and impurities incorporated in the film, Rutherford backscattering spectrometry (RBS), non-Rutherford backscattering spectrometry (NRBS), elastic recoil detection analysis (ERDA), and nuclear reaction analysis (NRA) were performed. IBA measurements were carried out using protons, helium, and oxygen ion beams. By exploiting the high cross section and the narrow width resonance of 15N (p, αγ) 12C nuclear reaction, 15N c ontent in the deposited films was precisely determined. To the best of our knowledge the precise measurement of N content in the UNCD film using the nuclear reaction 15N (p, αγ) 12C has been done for the first time. Our results showed that UNCD films incorporated with 15N have ~ 0.13 at.% N, 90-93 at.% of C, and 7-9 at.% of H. From the spectroscopic ellipsometry investigations, dielectric functions of the UNCD films were found to increase for the samples prepared with N2 gas added to the growth plasma. The UNCD film deposited with 0% of N2 has a high degree of light transmission in the visible and IR regions, whereas the transmission decreased as N2 content in the growth plasma was increased. Results obtained from UV/VIS and reflectance spectroscopes were in agreement with the SE findings on the UNCD films.

Access Setting

Dissertation-Open Access

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