How Many Types of Semiconductors are There

Introduction

Broadly speaking, we have two types of semiconductor devices which may again be classified further. Before we look into these various types of semiconductors in detail, we will understand what a semiconductor is and explore its important properties. The very invention of semiconductors has, indeed, proved to be a boon for the entire mankind as it has redesigned the electronic industry and is constantly showering its advantages which are making appliances smarter day by day. Isn’t it amazing that the laptop or the tablet or the smartphone on which we are reading this article, is only possible for these semiconductor devices and their further advancements? Let's examine it further by diving in.

What is a Semiconductor?

Well, the word “semi” indicates something in between two extremities. Actually, the semiconductor refers to the electrical entity whose properties of conducting current are somewhat in between the conducting characteristics of conductors and the blocking abilities of insulators.

It is well-known fact that conductors get their names because, on the application of a desired voltage across them, they can conduct electricity due to the presence of free electrons

Also, the insulators derive their titles because they insulate or block the passage of current through them due to their strongly adhered electrons in their outermost shells of electrons.

The Properties of The Semiconductors

Here are some of the important properties of semiconductors.

• The energy band gaps of semiconductors lie in between the energy band gaps of the conductors and that of the insulators.

• The semiconductors exhibit a resistivity less than that of conductors but much higher than that of the insulators.

• With the increase in the surrounding temperature affecting the semiconductors, they gain more conductivity.

• Semiconductors have a negative temperature coefficient of resistance.

• Though the semiconductors, mostly, behave as insulators at room temperature except for having some leakage current through them, we can increase their conductivities with the addition of certain specific impurities.

The Types of The Semiconductors

The broad classification of the semiconductors gives us these two varieties of semiconductors.

• Intrinsic semiconductors

The word intrinsic is self-explanatory to define these sorts of semiconductors. Intrinsic indicates some attribute that is naturally gifted. As such, these semiconductors are without any impurities and have charge carriers of their own.

Examples of intrinsic semiconductors are germanium and silicon.

• Extrinsic semiconductors

These kinds of semiconductors rely on the external introduction of impurities on them to have the required amount of charge carriers in them.

Extrinsic semiconductors are again of the following two types.

• The P-type semiconductors

In these extrinsic semiconductors, the trivalent elements, namely the boron, the Indium, the aluminium, etc are added as impurities to the intrinsic semiconductors.

There remains the scarcity of an electron ( one less than eight) in the valence shell of atoms of these extrinsic semiconductors, which gives rise to the presence of excess holes attributing to the positively charged carriers. Hence, we get the name positive or p-type semiconductors.

• The N-type semiconductors

In these extrinsic semiconductors, the pentavalent elements, namely phosphorous, arsenic, antimony, etc are added as impurities to the intrinsic semiconductors.

There remains the surplus of an electron (one more than eight) in the valence shell of atoms of these extrinsic semiconductors, which gives rise to the presence of excess electrons attributing to the negatively charged carriers. Hence, we get the name negative or n-type semiconductors.

The Different Uses of The Semiconductors

Among the numerous applications of semiconductors, we write some of the following.

• Semiconductors are the building blocks of diodes, transistors, etc.

• We will find its usage in the manufacturing of integrated circuits, thyristors, etc.

• Semiconductors are used in smart watches, smart television sets, etc.

• Semiconductors paved the way for the availability of miniature-sized electronic circuits, which in turn, has increased the storage capacity and the RAM (random access memory) capacity of our computers, laptops, etc.

• The electronic industry is dependent on semiconductors for its very existence in the present dominating way.

Conclusion

• The method of adding impurities to semiconductors is known as doping.

• The charge carriers in the semiconductors are both holes and electrons which are positive and negative respectively.

• The count of holes in any intrinsic semiconductor is exactly equal to the count of its electrons.

• The extrinsic semiconductors have either a surplus of electrons or an excess of holes in them.

• Intrinsic semiconductors are also termed pure semiconductors or undoped semiconductors. Also, they are referred to as i-semiconductors.

• Both the trivalent elements, like Indium, boron, and aluminium and pentavalent elements, like antimony, phosphorus, and arsenic, that are added as impurities in the semiconductors are termed dopants.