Physics Project Ldr
Theory
CONDUCTORS, INSULATORS AND CONDUCTIVITY
Conduction of electricity in electric circuits takes place due to the presence of excess electrons in materials called conductors. Electrons move in the direction in which the potential has been applied. The ability of a conductor to conduct electricity is directly proportional to the material’s area of cross section and inversely proportional to its length.
Where, G is conductance σ is conductivity A is area of cross section is length of conductor
Insulators are materials which have very low conductivity as a result they are unable to conduct electricity.
The conductivity of conductors (usually metals) is very high and the conductivity of insulators is very low.
SEMICONDUCTORS
A semiconductor has electrical conductivity intermediate to that of a conductor and an insulator. Semiconductors differ from metals in their characteristic property of decreasing electrical resistivity with increasing temperature.
The comprehensive theory of semiconductors relies on the principles of motion of electrons through a lattice of atoms. Current conduction in a semiconductor occurs via mobile or free electrons and holes, collectively known as charge carriers.
Certain pure elements found in Group IV of the periodic table are semiconductors. The most commercially important of these elements are silicon and germanium. Semiconductor materials are useful because their behaviour can be manipulated by the addition of impurities, known as doping .Doping a semiconductor with a small amount of impurity atoms greatly increases the number of charge carriers within it. When a doped semiconductor contains excess holes it is called "p-type", and when it contains excess free electrons it is known as "n-type".
Germanium, gallium arsenide, and silicon carbide are common dopants. A pure semiconductor is often called an “intrinsic” semiconductor. The electronic properties and the conductivity of a
CONDUCTORS, INSULATORS AND CONDUCTIVITY
Conduction of electricity in electric circuits takes place due to the presence of excess electrons in materials called conductors. Electrons move in the direction in which the potential has been applied. The ability of a conductor to conduct electricity is directly proportional to the material’s area of cross section and inversely proportional to its length.
Where, G is conductance σ is conductivity A is area of cross section is length of conductor
Insulators are materials which have very low conductivity as a result they are unable to conduct electricity.
The conductivity of conductors (usually metals) is very high and the conductivity of insulators is very low.
SEMICONDUCTORS
A semiconductor has electrical conductivity intermediate to that of a conductor and an insulator. Semiconductors differ from metals in their characteristic property of decreasing electrical resistivity with increasing temperature.
The comprehensive theory of semiconductors relies on the principles of motion of electrons through a lattice of atoms. Current conduction in a semiconductor occurs via mobile or free electrons and holes, collectively known as charge carriers.
Certain pure elements found in Group IV of the periodic table are semiconductors. The most commercially important of these elements are silicon and germanium. Semiconductor materials are useful because their behaviour can be manipulated by the addition of impurities, known as doping .Doping a semiconductor with a small amount of impurity atoms greatly increases the number of charge carriers within it. When a doped semiconductor contains excess holes it is called "p-type", and when it contains excess free electrons it is known as "n-type".
Germanium, gallium arsenide, and silicon carbide are common dopants. A pure semiconductor is often called an “intrinsic” semiconductor. The electronic properties and the conductivity of a
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