Electrical Properties

Ohm’s law

Ohm’s law

relates the current I—or time rate of charge passage—to the applied voltage V

electrical resistivity

dependence on

resistance, specimen

cross-sectional area,

and distance between

measuring points

Electrical conductivity

is used to specify the electrical character of a material. It is simply the reciprocal of the resistivity.

siemens per meter (S/m)

The SI units for electrical conductivity.

Metals

are good conductors, typically having conductivities on the order of 10⁷(Ω·m)–¹

Insulators

are materials with very low conductivities, ranging between 10−¹⁰ and 10−²⁰ (Ω·m)−¹

Semiconductor

Materials with intermediate conductivities, generally from 10−⁶ to 10⁴ (Ω·m)−¹

Ionic conduction

term for ionic materials, a net motion of charged ions is possible that produces a current.

Fermi energy

The energy corresponding to the highest filled state at 0K

Energy Band Structures In Solids

The number of free electrons depends on the electron energy band structure of the material.

Electronic Conduction

For most materials, an electric current results from the motion of free electrons, which are accelerated in response to an applied electric field.

electron energy band

each distinct atomic state may split into a series of closely spaced electron states in the solid to form.

free electrons

the electrons that participate in the conduction process

Holes

a charged electronic entity that can be found in semiconductors and insulators.

Matthiessen’s rule

the sum of the contributions from thermal vibrations, impurities, and plastic deformation—that is, the scattering mechanisms act independently of one another.

Intrinsic semiconductors

are those in which the electrical behavior is based on the electronic structure inherent in the pure material.

Extrinsic Semiconductor

the electrical characteristics of semiconductor are dictated by impurity atoms

n-type Extrinsic semiconductors

predominantly electrons are the charge carriers

p-type Extrinsic semiconductors

predominantly holes are the charge carrier

Donors

impurities that introduce excess electrons

Acceptor

impurities that introduce excess holes

diode

is an electronic device that allows the current to flow in one direction only

p–n rectifying junction

is constructed from a single piece of semiconductor that is doped so as to be n-type on one side and p-type on the other

flash memory

A relatively new and rapidly evolving information storage technology that uses semiconductor devices.

dielectric materials

is one that is electrically insulating (nonmetallic) and exhibits or may be made to exhibit an electric dipole structure

electric dipole

is a separation of positive and negative electrically charged entities on a molecular or atomic level.

Capacitance

related to the quantity of charge stored on either plate

permittivity of a vacuum

is a universal constant having the value of 8.85 × 10-¹² F/m.

Dielectric constant

is equal to the ratio which is greater than unity and represents the increase in charge-storing capacity upon insertion of the dielectric medium between the plates.

Polarization

The process of dipole alignment

Electronic polarization

It results from a displacement of the center of the negatively charged electron cloud relative to the positive nucleus of an atom by the electric field.

Ionic polarization

it occurs only in materials that are ionic. An applied field acts to displace cations in one direction and anions in the opposite direction, which gives rise to a net dipole moment.

Orientation polarization

is found only in substances that possess permanent dipole moment.

relaxation frequency

is taken as the reciprocal of this minimum reorientation time.

dielectric strength

sometimes called the breakdown strength, represents the magnitude of an electric field necessary to produce breakdown.

ferroelectrics

materials that exhibit spontaneous polarization that is, polarization in the absence of an electric field.

Piezoelectric

a material that generate electric field when mechanical stresses are applied.