I WOULD LIKE to express my deep gratefulness to my thesis adviser, Prof. Hans Kosina. He impressed me with his deep knowledge on semiconductor device modeling and physics and I learned a lot of material from numerous discussions we had. Prof. Siegfried Selberherr, who gave me the opportunity to join his research group, for providing the excellent infrastructure at the Institute for Microelectronics.

I would like to thank Prof. Tibor Grasser for his helps and advises on MINIMOS-NT. Furthermore, I thank Prof. Erasmus Langer, the head of the Institute for Microelectronics, who was a cooperative and helpful boss.

Discussions with Prof. David Pulfrey, from the University of British Colombia, on adaptive integration and small signal analysis of nanotube transistors are acknowledged.

I thank Prof. Emmerich Bertagnolli that he was willing to serve on my examination committee.

The special thanks goes to Oskar Baumgartner for careful proofreading of my thesis, Andreas Gehring and Enzo Ungersböck who have been always willing to help me with programing topics, Viktor Sverdlov for numerous discussion on quantum transport, Tesfaye Ayalew for giving me important advices for my life, Robert Entner and Martin Wagner for helping me to fix the problems of the operating systems on my PCs, and finally I am grateful to Alireza Sheikholeslami who helped me to have a smooth transition to my new life in Vienna.

I enjoyed the luck to work closely together with Markus Karner and other group members: Siddhartha Dhar, Stefan Holzer, Gerhard Karlowatz, Ling Li, Gregor Meller, Vassil Palankovski, Oliver Triebl, Martin Vasicek, Wilfried Wessner and Robert Wittmann.

Ewald Haslinger, Manfred Katterbauer, and Renate Winkler provided the background work at the Institute, which much too often is completely undervalued. All other members of the Institute for Microelectronics deserve gratitude for assistance and for the stimulating working atmosphere they create.

I am grateful to my wife Sara who provided me with love and understanding. Above all, I am forever indebted to my parents for continuous support.

M. Pourfath: Numerical Study of Quantum Transport in Carbon Nanotube-Based Transistors