Acknowledgment

First I would like to thank Prof. Siegfried Selberherr who gave me the honor to work at the Institute for Microelectronics. What makes this place so special? Not only the perfect infrastructure, the nice working atmosphere, and the large experience and knowledge gathered there, which all serves as a stable basis for further scientific research. Also not only the long term relations to the semiconductor industry worldwide, which make the members of the institute face real industrial problems. These are the output standards set by Prof. Selberherr on world-level and often even higher. The harder it is to keep up with these high requirements on one hand, the sweeter the feeling to have them matched on the other hand. I highly appreciate the opportunity to present results of my work at various conferences at all five continents and at leading semiconductor companies, such as Siemens, LSI Logic, Intel, Sony, Hitachi, and AMS. Dear Prof. Selberherr, thanks for everything I learned from You!

I also thank Prof. Erich Gornik who agreed to participate in the examining committee.

Next, I would like to thank Prof. Philip Philippov from TU Sofia for teaching me the basics of microelectronics and microelectronics technology. The work on my master's thesis on SiGe HBTs served as a good basis for my future work. In addition, Prof. Philippov gave me the first advices and recommendations for starting a doctoral study. I also thank Prof. Fritz Paschke and Prof. Wolfgang Fallmann for inviting me to visit TU Wien on the behalf of the Austrian Academy of Science and for supplying me with good recommendations.

I want to express my gratitude to Dr. Walter Kellner from Infineon Technologies AG (former Siemens AG) for giving me the opportunity to join his group as a free researcher. Thanks to him the III-V simulation was continuously supported by the corporate technology of Siemens over many years. The larger part of this thesis would not be possible without such valuable technical, theoretical, and financial support. I appreciate the opportunity to work in Münich in a ``brain-storming'' fashion. During my several stays there I enjoyed discussions with Dr. Rüdiger Schultheis, Dr. Jan-Erik Müller, and Andrea Bonacina, in which many useful ideas both on the simulation and the technology side were born. It is a memorable feeling to see the work effort paid by the practical application of its results. I also enjoyed nice evenings out with my former colleague Dr. Rudolf Strasser who is now with Infineon.

I would also like to thank Dr. Sheldon Aronowitz from LSI Logic Corporation, Milpitas, California for inviting me to spend a summer-internship in his group. I enjoyed excellent working climate and many fruitful discussions, especially with him, Dr. Helmut Puchner, and Dr. Nadya Belova. My stay was so nice that I included the possibility to work there in my future plans. I have to mention nice time out and discussions with my former colleague Dr. Claus Fischer, who is one of the creators of MINIMOS-NT and was with Intel at that time.

I am very grateful to all my colleagues at the Institute of Microelectronics. The atmosphere has always been a perfect source of motivation. It was great to be welcomed and introduced to MINIMOS-NT by Dr. Thomas Simlinger, now with IBM, and especially Dr. Martin Knaipp, now with AMS, with whom we still keep very good, also professional relations. It was pleasure to share office with Dr. Goran Kaiblinger who was the person ``infecting'' me to spend sometimes eighty, sometimes more, hours a week in working. Unfortunately, this style remained after he left. With his follower, Klaus Dragosits, we shared not only nice discussions during work, but also nice time in Puerto Rico and South Africa. I am very grateful to Prof. Hans Kosina who always took the time to answer my questions thoroughly sometimes even to the very depths of semiconductor physics. I would like to thank Dr. Tibor Grasser for his devotion to MINIMOS-NT which made the simulator so flexible and extendible. His programming expertise always served me as a good example when implementing a new code or reorganizing an old one. I thank him and Prof. Kosina for proofreading this thesis. My gratitude is also due to Christian Troger and Thomas Binder who made my life easy in the Linux environment. I thank also all others who were always willing to help, discuss some topic, or just go out for a beer.

I have to specially mention a long-standing co-worker and friend, Rüdiger Quay. Together we proved that long distance cannot be an obstacle for effective co-actions. He was always ready to enter discussions of new topics, ideas, and results. For the several hundreds of mails we shared, the country we were working in, or sometimes the continent, did not matter. This was also proved in numerous common publications. I also enjoyed sharing few evenings out with him in Vienna, Freiburg, London, and Seattle.

Last, I want to thank my parents, without whom I would never have been able to achieve so much. I honor the memory of the three of my grandparents whom I lost during my first two years at the institute. I cordially thank my son for not forgetting me, even though he had so seldomly the opportunity to see me. I especially wish to express my love for Dessi who only knows the real price of this dissertation as we suffered and paid it together. I thank for her endless love, patience, and understanding.