What is a semi-conductor? With the help of simple line-drawings, describe semi-conductor devices and their uses

What is a semi-conductor? With the help of simple line-drawings, describe semi-conductor devices and their uses.
Ans.
Semiconductors are the materials possessing very low electrical conductivity. These are neither conductor, nor insulator. Conductivity of a semiconductor increases considerably when a certain amount of impurities are added to them. For e.g. silicon and germanium. These are used to fabricate solar cells. Some applications of semiconductors are as follows:
Computer chips,
both for CPU and memory
Communication devices
Electrical and electronic gadgets
Converting electric supply from A.C. to D.C. Amplify signals Audio and video systems, etc. are composed of semiconductor materials Transistors Integrated circuit chips P-n junction diode/triode There are various metals like copper, iron or aluminium. They are all good conductors of electric current. You also know that many materials like wood, plastic or quartz do not conduct current. Such materials are called insulators. A semiconductor, ability to conduct electric current is greater than that of an insulator but less than that of metals. Silicon and germanium are the most commonly used semiconductors. Some other compounds like gallium arsenide, indium antimonide are also used. as the name indicates, is a material whose The ability of semiconductors to conduct electricity depends critically upon their purity, or rather their impurity. A pure crystal of silicon or germanium acts more or less as an insulator. However if an added to the crystal it becomes more conductive. By the way, "impurity" does not mean a 50-50 mixture or even one part of impurity in ten parts of silicon. In useful semiconductors, a ton of silicon may have 1 mg of the element arsenic. Even the tiny bit of arsenic contributes surplus electrons to silicon, which then becomes a better conductor. Such a piece of silicon would be called an n-type semiconductor. On the other hand, a like amount of boron would cause a different kind of conduction to take place and the piece of silicon so treated would be called p-type semiconductor. The word 'doping' is used by scientists to describe introduction of such small impurities. impurity is