What is Semiconductor? Properties, Applications, Types

Silicon
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What is Semiconductor?

In simple words, a semiconductor is a material that has electrical conductivity properties between those of conductors (such as metals) and insulators (such as non-metals). The semiconductor material is the heart of electronics engineering. We cannot think about electronics without semiconductor materials. Most electronic devices use semiconductor materials for making their internal components. Let’s learn about semiconductors very simply.

             Conductor means which conducts current. According to its name, ‘Semiconductor’ implies that it cannot work completely as a conductor material, but it conducts current. So it is not a good conductor. On the other hand, the semiconductor is not a good insulator. The electrical property of a semiconductor material lies between the Conductor and insulator material.

Let’s learn why a semiconductor is not a good conductor or not a good insulator.

Each material has two bands Conduction Band and Valance Band, and the gap between these two Bands is called Energy Band Gap. The free electrons of the conduction Band participate in current conduction. In a semiconductor, the bonds between neighboring atoms are not very strong only moderately strong. Therefore this bond can easily break. When bonds are broken, electrons easily come from the valence band to the conduction band which participates in current conduction. In the semiconductor, the energy band gap is very small.

Germanium
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Properties of Semiconductor Material

1. Semiconductor Material is not a good conductor or not a good insulator, its electrical properties lie between Conductor and insulator material. Semiconductors can conduct electricity but not as well as metals. They are not as good as conductors like metals but they are better than insulators like rubber.
2. Semiconductors have a specific energy band gap that determines how easily electrons can move. This gap acts like a hurdle that electrons need to jump over to move around.
3. If the temperature of the semiconductor is increased then its resistance will be decreased. So when it gets hotter, they conduct electricity better.
4. Semiconductors have both electrons and holes as charge carriers. Electrons are negatively charged and move around easily, while holes act like positive particles that can also move.
5. We can change the behavior of semiconductors by adding impurities. Adding impurities can either give more electrons or create empty spaces called holes.
6. We can control the conductivity of semiconductors by applying an electric field or changing the impurity level. This allows us to control the flow of electricity, which is important in electronic devices.

Types of Semiconductor

According to having impurities or not there are two types of semiconductors as follows,

1. Intrinsic semiconductor: 

A semiconductor without any impurities is called an Intrinsic semiconductor. It is a pure semiconductor material that has no intentional impurities added to its crystal structure. In an intrinsic semiconductor, the number of free electrons (negative charge carriers) and holes (positive charge carriers) is equal. The conductivity of an intrinsic semiconductor depends on temperature and the energy gap between the valence band and the conduction band. Intrinsic semiconductors have a well-defined energy gap between the valence and conduction bands. For silicon, a commonly used intrinsic semiconductor, the energy gap is approximately 1.1 electron volts (eV).

2. Extrinsic semiconductor: 

The semiconductor doped by suitable impurities is called an Extrinsic semiconductor. Unlike an intrinsic semiconductor, which is a pure semiconductor, an extrinsic semiconductor contains deliberate impurities to enhance its conductivity or alter its behavior. The intentional doping of extrinsic semiconductors allows for greater control over their electrical characteristics. By adding specific impurities, such as phosphorus or boron, the number of charge carriers (electrons or holes) can be increased or decreased, respectively.

There are two types of Extrinsic semiconductors,

1. P-type (The semiconductor doped by trivalent atom)

2. N-type (The semiconductor doped by pentavalent atom)

Uses of Semiconductor Material

1. Semiconductor materials are used in Integrated Circuits (ICs) which are tiny chips used in computers, smartphones, and devices. They store information, process data, and perform calculations.

2. Transistor is a very important component in the field of the electronics industry. They control electronic signals and are found in almost everything electronic, like TVs and radios. Transistors are basically made of semiconductor materials.

3. Semiconductor materials are used to make diodes that allow electricity to flow in one direction and are used in devices that convert AC to DC, like power adapters, and in circuits to protect against wrong currents.

4. LEDs or Light Emitting Diodes are also semiconductor devices that emit light when an electric current passes through them. They are used in lighting applications, display screens, indicators, and backlighting for electronic devices.

5. Semiconductors are used in various types of sensors, such as temperature sensors, pressure sensors, light sensors, and motion sensors. These sensors are vital in many applications, including environmental monitoring, automotive systems, and medical devices.

6. Power semiconductor devices, such as insulated gate bipolar transistors (IGBTs) and power diodes, are used in power electronic systems for efficient control and conversion of electrical power. They are found in electric vehicles, renewable energy systems, industrial motor drives, and power supplies.

Examples of Semiconductor Materials

Some examples of intrinsic semiconductors are Silicon (Si), Germanium (Ge), Zinc oxide (ZnO), Gallium arsenide (GaAs), etc.

Some examples of extrinsic semiconductors are,

N-type semiconductor: Silicon (Si) with Phosphorus (P) doping, Germanium (Ge) with Arsenic (As) doping, Gallium Arsenide (GaAs) with Silicon (Si) doping, Indium Antimonide (InSb) with Tellurium (Te) doping, etc.

P-type semiconductor: Silicon (Si) with Boron (B) doping, Germanium (Ge) with Gallium (Ga) doping, Gallium Arsenide (GaAs) with Zinc (Zn) doping, Indium Phosphide (InP) with Magnesium (Mg) doping, etc.

Read Also: 

• Main Difference between Extrinsic and Intrinsic Semiconductors
• Actual Difference Between SCR and IGBT
• LDR Full Form, Symbol, Construction, Connection Diagram
• MOSFET VS JFET | The Main Differences
• What is Silicon Controlled Rectifier(SCR), Construction, symbol, Working, Application
• Enhancement VS Depletion MOSFET Advantages, Applications

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