Acknowledgment

I would like to take this opportunity to acknowledge those who have provided the help and guidance to complete my doctoral degree at the Institute for Microelectronics, Vienna University of Technology.

First and foremost I would like to thank my adviser Prof. Siegfried Selberherr, dean, Faculty of Electrical Engineering and Information Technology for his strong support, guidance and encouragement throughout my study at the Institute for Microelectronics. His great experience guided me to enlarge my knowledge on the semiconductor fields, and his enormous trust gave me both of the freedom and pressure to quest new world. I always keep in mind his words to the students 'Time goes very fast$$'.

I would like to express my appreciation to Prof. Emmerich Bertagnolli, head, Institute of Solid State Electronics who agreed to participate in my examining committee on a very short notice. Furthermore, my special thanks have to be expressed to Prof. Erasmus Langer, head, Institute for Microelectronics who gave the students an excellent environment for study. I am also grateful to Prof. Hans Kosina for his kind support from the beginning of my settlement and for his excellent lecture on TCAD.

Prof. Tibor Grasser guided me to enter TCAD with Minimos-NT and he gave me excellent comments on my thesis and papers, I appreciate his time and patience. Furthermore, I like to enjoy his professional piano concert.

I am grateful to my roommates. Dr. Robert Klima guided me to the three-dimensional simulator and gave me excellent support. I would like to thank Dr. Rodrigo Rodríguez-Torres for intensive discussions on semiconductor devices, Stephan Wagner for many explanations of linear solver systems and several accurate corrections of my Minimos-NT commands, and Wilfred Wesner for nice introduction to three-dimensional meshing. I would like to thank to Dr. Andreas Gehring for several discussions on semiconductor physics and for his nice support on using Minimos-NT. I had a good time with Dr. Tesfaye Ayalew for discussing about silicon carbide devices. I will never forget the good times I spent with my colleagues Dr. Thomas Binder, Dr. Clemens Heitzinger, Alireza Sheikholeslami, Hajdin Ceric, Stephan Enzo Ungersböck, Robert Entner, Christian Hollauer, Stefan Holzer, Dr. Robert Kosik, Dr. Vassil Palankovski and Dr. Klaus Dragosits who let me share their knowledge on semiconductor devices.

I thank Austriamicrosystems AG, Unterpremstätten, for nice discussions on semiconductor devices. Especially, I would like to give my thanks to Martin Schrems, Rainer Minixhofer, Martin Knaipp, Verena Vescoli, and Georg Röhrer.

My special thanks have to be expressed to Prof. Baik Hyung Han, dean of Natural Science, Hanyang University and Prof. Choongwon Kim, Chosun University for their endless support.

Above all I wish to thank my parents for their love, and special thanks go to my brother and sister, Jongjin and Mijeong for their continuous support. Last but certainly not least I wish to express my deep love to my wife Yangmi, and to my children Jaesoon and Joohyun.