Fundamentals of Microelectronics, 2nd Edition

Basic Physics of Semiconductors

Microelectronic circuits are based on complex semiconductor structures that have been under active research for the past six decades. While this book deals with the analysis and design of circuits, we should emphasize at the outset that a good understanding of devices is essential to our work. The situation is similar to many other engineering problems, e.g., one cannot design a high-performance automobile without a detailed knowledge of the engine and its limitations.

Nonetheless, we do face a dilemma. Our treatment of device physics must contain enough depth to provide adequate understanding, but must also be sufficiently brief to allow quick entry into circuits. This chapter accomplishes this task.

Our ultimate objective in this chapter is to study a fundamentally important and versatile device called the “diode.” However, just as we need to eat our broccoli before having dessert, we must develop a basic understanding of “semiconductor” materials and their current conduction mechanisms before attacking diodes.

In this chapter, we begin with the concept of semiconductors and study the movement of charge (i.e., the flow of current) in them. Next, we deal with the “pn junction,” which also serves as diode, and formulate its behavior. Our ultimate goal is to represent the device by a circuit model (consisting of resistors, voltage or current sources, ...