First of all I would like to thank Prof. Siegfried Selberherr, the head of the Institute for Microelectronics, who was the supervisor for this thesis and an excellent manager in that he always provided an outstanding working environment and a stimulating research atmosphere. I am grateful for his pressing, whenever I needed it, and his encouragement, whenever he felt it necessary.
I do express my sincere gratitude to the research laboratories of Siemens AG, Munich, for granting me a scholarship. Without this financial support my research would not have been possible. Further, my work has been partially supported by the ``Forschungsförderungsfonds für die gewerbliche Wirtschaft, Projekt 2/285.''
I wish to thank Llanda Richardson from Digital Equipment Corp. and Marius Orlowski from Motorola Inc. for inviting me to work in their research groups. I greatly appreciated this opportunity to gain valuable experience for both my professional and personal life. Thanks to Matt Noell from Motorola for all the discussions and the exciting time in Austin. I acknowledge the excellent cooperation with Gerd Nanz and Christian Schiebl from DEC's Campusbased Engineering Center in Vienna, and with Gerhard Hobler from the ``Institut für Allgemeine Elektrotechnik und Elektronik''.
I would like to thank most warmly all my colleagues at the institute for valuable contributions, efficient computer support and many fruitful discussions. My special thanks go to my room-mates Hannes Stippel and Hans Kosina who shared the good times and took the bad times.
Last but not least, I emphatically thank my and Sabine's family for continuous encouragement and support.