First and foremost, I would like to express my deepest thanks to my advisors, Prof. Siegfried Selberherr and Doz. Viktor Sverdlov, for giving me the opportunity to carry out my doctoral study at the Institute for Microelectronics. Siegfried provided an excellent working atmosphere, where I had the freedom to pursue various ideas and the possibility to enhance my research skills and to attend numerous international conferences. Viktor continuously guided and supported me and I really appreciate his motivation as well as constructive and frank comments which significantly improved the quality of my work.

I am also very grateful to Prof. Bernd Meinerzhagen who kindly agreed to take part in the examining committee.

Furthermore, I am indebted to Thomas Windbacher for his consistent guidance on my research during the last two years, the German translation of the abstract, and the careful proofreading of the thesis. He has been always willing to provide his feedback whenever I needed.

My sincere thanks also goes to Prof. Hans Kosina for his considerable support at the very beginning of my doctoral research and Mahdi Pourfath for his help and kindness made adapting to my new life in Vienna easier.

I want to express my gratitude to Prof. Erasmus Langer who has been a very cooperative head and other members of the institute for their support over the recent years, among them Wolfhard H. Zisser, Hossein Karamitaheri, Johann Cervenka, Franz Schanovsky, Manfred Katterbauer, Ewald Haslinger, Renate Winkler, and Markus Kampl.

Last but not the least, I am ever thankful to my friend and teacher Kake Foad and to my family members; my parents Mehn and Heme-El, my lovely wife Sureya, and my sisters Şwa and Şma for their love, support, patience, and trust.