Writing and finishing this thesis wouldn't have been possible with the support of my colleagues at the Institute of Microelectronics. The most important person for my work is definitely my advisor Prof. Tibor Grasser, who didn't get tired of motivating me to continue and especially to finally finish writing my thesis. Special thanks also go to Prof. Martin Gröschl, who agreed on a very short notice to be the second reviewer. I also want to thank Prof. Hans Kosina, Prof. Erasmus Langer, and Prof. Siegfried Selberherr, in whose projects I could participate in times when funding was short. In the daily organizational work Ewald Haslinger, Manfred Katterbauer, and Renate Winkler were always at hand to help and to give advice.
I also want to thank the companies Infineon Villach, ams, and Sony Japan for giving their share of the financial support. For the job opportunity and financial support beside the university I want to acknowledge Markus Karner and Christian Kernstock, the founders of Global TCAD Solutions.
Writing this thesis was a long process and luckily there were many colleagues who were there for help and discussions. Also chats during coffee breaks and the many private activities were important for the good collaboration. I have the best memories of my early days at the institute among my room mates Gerhard Karlowatz, Victor Sverdlov, and Wilfried Wessner. Also my other colleagues, especially Johann Cervenka, Robert Entner, Stefan Holzer, Philipp Schwaha, Enzo Ungersböck, and Martin Wagner were responsible for this very good atmosphere. These people helped me to get to know how things are working at the institute and how to get along in this new environment. I will not forget the common activities, including a marathon run, a trip to India joining the wedding of our colleague Siddhartha Dhar, going for a hike in France, and the common motorcycle trips. I am really happy to still be in contact with most of these colleagues.
Among the people who joined the institute later than I did, I want to specially thank Martin Vasicek, Wolfgang Gös, and Stanislav Tyaginov. Together with Johann, they were in charge of proofreading this thesis. Stanislav was always there to check my texts and to give scientific advise, sometimes even during long night shifts. An office which I will definitely remember was occupied by Philipp Hehenberger, Franz Schanovsky, and Paul-Jürgen Wagner. In this office every single word could trigger one of the most intellectual and philosophical discussions. More people I want to thank for the good collaborations are Oskar Baumgartner (viva Las Vegas), Markus Bina (thanks for the good work done in MINIMOS-NT), Neophytos Neophytou (sorry for the idea of going downhill skiing), Zlatan Stanojevic, Ivan Starkov (thanks for the simulation results I could borrow), and Thomas Windbacher. And thanks to all the colleagues I didn't mention here but who are also responsible for the in general good time I had at the Institute of Microelectronics.
Finally, I want to thank my family. My parents Erika and Wilhelm didn't stop motivating me and I wouldn't have joined the institute without my father's convincing words. My wife Martina always tried to cheer me up and supported me, also in times of my biggest frustrations. Also a big ``thank you'', for the patience with me during the last months, in which I was at home just for sleeping, because there was no time left between studies and work.