Properties of Semiconductor

The electrical characteristics of semiconductors are unique. A conductor is something that conducts electricity, while an insulator is something that doesn’t. Semiconductors are materials that have properties that fall in the middle of the spectrum.

Resistivity is a measurement of electrical properties. Gold, silver, and copper are good conductors of electricity because they have low resistance. Rubber, glass, and ceramic insulators have a high resistance to electricity and make it difficult to pass through them. Semiconductors fall somewhere in the middle of these two categories. For example, their resistance may alter as a function of temperature. Electricity does not travel through them at low temperatures. When the temperature rises, though, electricity easily goes through.

Properties of semiconductor

Variable electrical conductivity

Because a current requires the flow of electrons, semiconductors are poor conductors in their native state because their valence bands are full, inhibiting the entire flow of new electrons. Doping and gating are two ways that have been discovered to make semiconducting materials act like conducting materials. The n-type and p-type variants are the results of these changes. These terms allude to an abundance or deficiency of electrons. A current would run through the material if there were an equal number of electrons.

Heterojunction

When two semiconducting materials with distinct dopants are connected, heterojunctions form. P-doped and n-doped germanium, for example, could make up a configuration. The different doped semiconducting materials exchange electrons and holes as a result of this. There would be an excess of electrons in n-doped germanium and an excess of holes in p-doped germanium. Recombination, which causes the migrating electrons from the n-type to come into touch with the migrating holes from the p-type, causes the transfer to continue until an equilibrium is established.

Light emission

Excited electrons in certain semiconductors can relax instead of producing heat by radiating light. Light-emitting diodes and fluorescent quantum dots are made with these semiconductors.

High thermal conductivity

Heat dissipation and improved thermal management of electronics can be achieved using semiconductors with high thermal conductivity.

Thermal energy conversion

Semiconductors have high thermoelectric figures of merit and large thermoelectric power factors, making them ideal for thermoelectric generators and coolers.

Resistivity

With increasing temperature, the energy gap between the conduction and valence bands in semiconductors shrinks. At high temperatures, the valence electrons in semiconductor materials gain enough energy to break the covalent bond and enter the conduction band. At high temperatures, this results in a larger number of charge carriers in the semiconductor. The resistivity of the semiconductor is reduced as the charge carrier concentration increases. The semiconductor gets more conductive as the resistance of the material falls as the temperature rises. At high temperatures, a semiconductor has outstanding conductivity.

Temperature coefficient of resistance

A semiconductor has a negative temperature coefficient of resistance. As the temperature rises, the resistance decreases. The semiconductor’s conductivity rises as a result of the increased number of charge carriers accessible for recombination. With rising conductivity, the semiconductor material’s resistivity decreases, resulting in a negative temperature coefficient of resistance. The temperature coefficient of resistance is the resistance-to-change factor per degree Celsius of temperature change. The Greek lower-case letter “alpha” (α) is the symbol for this factor. When a material has a positive coefficient, it means its resistance increases as the temperature rises.

Current flow

The movement of charge carriers in the conduction and valence bands causes current flow in semiconductors. In the conduction band, electrons are mobile, while holes are mobile in the valence band. Drift current and diffusion current are the two main components of the current, however one or the other may prevail in some circumstances. Drift current arises in the presence of an electric field that causes a net motion of positively charged carriers in the same direction as the field and negatively charged carriers in the opposite direction as a result of the force it exerts to act on each charge carrier.

In a semiconductor, current flow is like how water flows. In rivers and pipes, no water flow is produced. The flow is visible there. When water changes its potential from high to low, it flows. This could range from a greater elevation such as a mountain, hill, or water tower to a lower elevation such as an ocean, lake, or kitchen sink. The flow passes through rivers, creeks, and pipes along the way, with dikes, dams, and valves allowing it to be regulated.

Semiconductors work similarly to transistors. The power supply has a high potential, while the earth has a low one. Current flows via silicon devices such as resistors, capacitors, and transistors, which are made up of small metal wires imprinted onto the silicon. Most of the flow control work is done by transistors. In a digital circuit, the transistor controls the current flow. It’s termed a gate because it allows or prevents current from flowing to the next sub-circuit. An analogue circuit’s transistor controls the amount of current that can flow like a faucet.

Conclusion

Gapless semiconductors and semiconductors with an energy gap of less than 0.1 eV have unique features that bring up a wide range of possibilities for practical applications. The extraordinary sensitivity of these materials’ band structures to external effects like magnetic fields, electromagnetic radiation, pressure, temperature, and contaminants makes them exceedingly valuable. Semiconductors, also known as integrated circuits (ICs) or microchips, are composed of pure elements such as silicon or germanium, as well as compounds like gallium arsenide. Small amounts of impurities are added to these pure elements in a process known as doping, resulting in dramatic changes in the material’s conductivity.

Semiconductors play a crucial role in the production of electrical devices, thus they’re everywhere. Consider what life would be like if you didn’t have access to any technology devices. Smartphones, radios, televisions, laptops, video games, and advanced medical diagnostic devices would not be available.