Semiconductor Electronics

SEMICONDUCTOR ELECTRONICS

Electronics is clearly the winner of the day – John Ford.

LEARNING OBJECTIVES

In this unit, the students are exposed to,

• Energy band diagram in semiconductors

• Types of semiconductors

• Formation of p-n junction diode and its V-I characteristics

• Rectification process

• Special purpose diodes

• Transistors and their immediate applications

• Digital and analog signals

• Logic gates

• Boolean algebra

• De Morgan’s theorem

INTRODUCTION

Electronics has become a part of our daily life. All gadgets like mobile phones, computers, televisions, music systems etc work on the electronic principles. Electronic circuits are used to perform various operations in devices like air conditioners, microwave oven, dish washers and washing machines. Besides this, its applications are widespread in all fields like communication systems, medical diagnosis and treatments and even handling money through ATMs.

Evolution of Electronics:

The history of electronics began with the invention of vacuum diode by J.A. Fleming in 1897. This was followed by a vacuum triode implemented by Lee De Forest to control electrical signals. This led to the introduction of tetrode and pentode tubes.

Subsequently, the transistor era began with the invention of bipolar junction transistor by Bardeen, Brattain and Shockley in 1948 for which Nobel prize was awarded in 1956. The emergence of Germanium and Silicon semiconductor materials made this transistor gain popularity, in turn its application in different electronic circuits.

The following years witnessed the invention of the integrated circuits (ICs) that helped to integrate the entire electronic circuit on a single chip which is small in size and cost-effective. Since 1958 ICs capable of holding several thousand electronic components on a single chip such as small- scale, medium-scale, large-scale, and very- large scale integration started coming into existence. Digital integrated circuits became another robust IC development that enhanced the architecture of computers.All these radical changes led to the introduction of microprocessor in 1969 by Intel.

The electronics revolution, in due course of time, accelerated the computer revolution. Now the world is on its way towards small particles of nano-size, far too small to see. This helps in the miniaturization to an unimaginable size. A room-size computer during its invention has now emerged as a laptop, palmtop, iPad, etc. In the recent past, IBM revealed the smallest computer whose size is comparable with the tip of the rice grain, measuring just 0.33 mm on each side.

Electronics is the branch of physics incorporated with technology towards the design of circuits using transistors and microchips. It depicts the behaviour and movement of electrons and holes in a semiconductor, electrons and ions in vacuum, or gas. Electronics deals with electrical circuits that involve active components such as transistors, diodes, integrated circuits, and sensors, associated with the passive components like resistors, inductors, capacitors, and transformers.

This chapter deals with semiconductor devices like p-n junction diodes, bipolar junction transistors and logic circuits.

Passive Components: components that cannot generate power in a circuit. Active components: components that can generate power in a circuit.

The world’s first computer ‘ENIAC’ was invented by J. Presper Eckert and John Mauchly at the University of Pennsylvania. The construction work started in 1943 and got over in 1946. It occupied an area of around 1800 square feet. It had 18,000 vacuum tubes and it weighed around 50 tons.