This class is the second class of an introduction to the physical principles of semiconductor devices and their fabrication technology. It is intended to apply the basics of semiconductor physics to semiconductor devices such as the optoelectronic diodes, Schottky diodes, metal oxide semiconductors, and transistors. The success in understanding the semiconductor devices is not only to work problems that exercise the concepts but also to practice numerically the performance of the devices. Therefore, three or four problems at the end of each chapter are assigned to the homework every week. And two numerical calculations are given to practice the performance of the devices in the middle of the semester. The class includes devices based on both silicon and compound semiconductors, to reflect the continuing growth in importance for compounds in optoelectronic and high-speedd evice applications.