In a semiconductor, the energy gap is very small as shown in the figure. In conductors, valence band and conduction band are overlapping each other means there is no gap between that. At low temperature, the semiconductor valence band is completely filled and conduction band is empty so that it behaves like an insulator or a poor conductor. At a high temperature or even at room temperature, some electrons are passes to the conduction band form valance band. These increase the conductivity of the semiconductor.
With the increase in the temperature, the conductivity of semiconductor increases. The conductivity of semiconductor material changes with the variation of temperature. This may be an important point for the semiconductor material. Here we see in detail about the effect of temperature on a semiconductor. We will see the effect on the semiconductor with two temperature. At absolute zero temperature : At absolute zero temperature, all electrons are tightly held by semiconductor atoms.
At this temperature, the co-valance bonds are so strong that there are no free electrons available. Therefore, at this temperature semiconductor crystal behaves like an insulator. At above absolute zero temperature : When the temperature rises, some of the co-valance bonds are break due to thermal energy.
Breaking bonds creates free electrons. So some few electrons exist in the semiconductor which can flow current through it. There are many semiconductors are available but some have practical applications in electronics. Silicon Se and Germanium Ge are widely used semiconductors. These semiconductors are widely used because the energy required by this two material for release electron from their valance band is too small. Silicon requires 1. Silicon and germanium are the basic examples of semiconductors.
You can refer this power system book pdf for your further study also. Download — vk Mehta book pdf. In an Intrinsic semiconductor, the electron-hole pair created even at room temperature. In this type of semiconductor, When the voltage applied between this material, current passes through the material due to free electrons and holes.
You can refer to this figure. Free electrons are produced due to the breaking of the co-valance bond by thermal energy. At the same time holes are created in the co-valance band. Therefore, total current passes through semiconductor are the sum of current due to electrons and holes. Current passes through the external wire is only depended upon electron. So you might think what about holes? For that refer above figure, holes being positively charged move towards the negative terminal B.
As the holes reach the negative terminal electrons enter the holes, thus canceling them. At the same time, at terminal A, electrons are attracted away from the atom to the battery terminal. Hence, new holes are created at terminal A and repeat this process. So the main property of intrinsic semiconductor is current is passing through this type of semiconductor by holes and electron both. Intrinsic semiconductors have a poor conductivity at the room temperature.
For the increase in their conductivity impurities are added to the semiconductor material. This type of semiconductor having some impurities called extrinsic semiconductor. The process of adding impurities in the semiconductor is called as doping. The main purpose of doing is to increase the numbers of the electrons or holes in the semiconductor crystal. Depending upon the impurities added, p-type or n-type semiconductor can be decided. When pentavalent impurity added to the semiconductor material, a large number of free electrons are produced in the semiconductor.
This type of semiconductor called n-type semiconductors. You can also refer difference between p type and n type semiconductor material. When trivalent impurity added to the semiconductor material, holes are created into the semiconductor. This type of semiconductor called n-type semiconductor.
So here the property of extrinsic semiconductor is that current is passing through semiconductor by only electrons. Semiconductors are extremely useful in making of electronic devices. The transistor which is made up from the semiconductor is widely used as an electric switch in circuits. As per the above, we see silicon. Germanium and Gallium arsenide is the example of semiconductor material. The silicon Si is the most widely used semiconductor material.
Its useful temperature range makes it currently the best compromise among the various competing materials. Silicon used in semiconductor device manufacturing is presently fabricated into bowls that are large enough in diameter to allow the manufacture of mm 12 in.
Germanium Ge was widely used semiconductor material in past. Recent silicon semiconductor is used in most applications. Thermal sensitivity of germanium is comparatively low than a silicon semiconductor. So silicon is going to first preferred semiconductor.
Gallium arsenide GaAs is also a semiconductor device which is widely used with high-speed devices. This semiconductor is more expensive than other semiconductors. Semiconductors are useful for making extremely small electronics device with which evolution of modern electronics possible. With the semiconductors two terminals, three terminals and four terminal devices are made. We list out all applications and uses of semiconductors above, We saw semiconductors are everywhere in our life or industry.
If you have any question related to this article kindly comment below. Your email address will not be published. Skip to content Search for:. Why semiconductors are used? Hope now you understand why semiconductors are used instead of conductors and semiconductors. Advantages of semiconductors Here are some advantages of semiconductors which makes semiconductor useful in our everyday life.
Applications of semiconductors in industry Day by day with the increase in technology semiconductor requirement is also going to improve. Semiconductor device materials As per the above, we see silicon. Which devices are made with semiconductors?
Two terminal devices Diode — which is made up by two semiconductors. It made with a p-n junction. The diode only passes current through it when it is in forwarding bias. Diodes are used rectifier circuits which converts A. Base, collector, and emitter. Transistors are used in switching applications and as an amplifier. More Articles. Leave a Reply Cancel reply Your email address will not be published.
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