Semiconductors

Semiconductors. Bannari Amman I.O.T. SWETHA R | 181EI164.

A s emiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic copper, and an insulator, such as glass. Semiconductors are an essential component of electronic devices, enabling advances in communications, computing, healthcare, military systems, transportation, clean energy, and countless other applications..

Sa:O. Commonly used semiconductors: Silicon Germanium Gallium Arsenide.

Resistivity: 10-5 to 106 Ωm Co nductivity: 105 to 10-6 mho/m Temperature coefficient of resistance: Negative Current Flow: Due to electrons and holes.

Semiconductor acts like an insulator at Zero Kelvin. On increasing the temperature, it works as a conductor. Due to their exceptional electrical properties, semiconductors can be modified by doping to make semiconductor devices suitable for energy conversion, switches, and amplifiers. Lesser power losses. Semiconductors are smaller in size and possess less weight. Their resistivity is higher than conductors but lesser than insulators. The resistance of semiconductor materials decreases with the increase in temperature and vice-versa..

s.No (i) (ii) (iii) (iv) (v) Extrinsic Semiconductor Intrinsic Semiconductor These are pure semiconductors. These are impure semiconductors. Its conductivity is large. Its conductivity is poor. In n-type electrons are in majority Here the number of electrons whereas in p-type holes are in majorit and holes are equal. In n-type Fermilevel lies near the Fermi energy level lies at the bottom of conduction band and in centre of forbidden energy gap. p-type near the top of valance bas A semiconductor in an extremely i A semiconductor in an extrem- pure form is known as an extrinsi ely pure form is known as an semiconductor. intrinsic semiconductor. Ex. For N-type Phosphorous (P), Ex. Silicon and Germanium Antimony (Sb), Arsenic (As), for P-type Gallium (Ga), Indium (In), Aluminium(Al), Boron (B)..

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