Conductor Insulator and Semiconductor:
Conductor Insulator and Semiconductor are made up of atoms. These atoms contribute to the electrical properties of a Conductor Insulate and Semiconductor material, including its ability to conduct electrical current. For purposes of discussing electrical properties, an atom can be represented by the valence shell and a core that consists of all the inner shells and the nucleus. This concept is illustrated in a Figure for a carbon atom. Carbon is used in some types of electrical resistors. Notice that the carbon atom has four electrons in the valence shell and two electrons in the inner shell. The nucleus consists of six protons and six neutrons, so the +6 indicates the positive charge of the six protons. The core has a net charge of +4 (+6 for the nucleus and -2 for the two inner-shell electrons).
An Insulator could be a material that does not conduct electrical current under traditional conditions. Most good insulators are compounds instead of a single part material and have terribly high resistivities. Valence electrons are closely bound to the atoms in a Insulator; thus, there are very few without charge electrons in an insulator. An Insulator have full valance shell.
Examples of insulators are rubber,plastics, glass, mica, and quartz.
A conductor is a material that easily conducts electrical current. Most metals are good conductors. The best conductors are single-element materials, such as copper (Cu), silver (Ag), gold (Au), and aluminum (Al), which are characterized by atoms with only one valence electron very loosely bound to the atom. These loosely bound valence electrons become without charge electrons. Therefore, in a conductive material the without charge electrons are valence electrons. Conductor atom have 1 to 3 valance electrons.
A semiconductor is a material that is between conductors and insulators in its ability to conduct electrical current. A semiconductor in its pure (intrinsic) state is neither a good conductor nor a good insulator. Single-element semiconductors are antimony (Sb), arsenic (As), astatine (At), boron (B), polonium (Po), tellurium (Te),
silicon (Si), and germanium (Ge). Compound semiconductors such as gallium arsenide,indium phosphide, gallium nitride, silicon carbide, and silicon germanium are also commonly used. The single-element semiconductors are characterized by atoms with four valence electrons. Silicon is the most commonly used semiconductor. Semiconductor atom have 4 valance electrons.
Next to silicon, the second most
common semiconductive material
is gallium arsenide, GaAs. This is a
crystalline compound, not an
element. Its properties can be
controlled by varying the relative
amount of gallium and arsenic.
GaAs has the advantage of
making semiconductor devices that
respond very quickly to electrical
signals. This makes it better than
silicon for applications like
amplifying the high frequency
(1 GHz to 10 GHz) signals from TV
satellites, etc. The main
disadvantage of GaAs is that it is
more difficult to make and the
chemicals involved are quite often
Lets have a Look on Energy Diagram of Conductor Insulator and Semiconductor:
- The difference in energy between the valence band and the conduction band is called an energy gap or band gap.
- This is the amount of energy that a valence electron must have in order to jump from the valence band to the conduction band. Once in the conduction band, the electron is easy to move throughout the material and is not tied to any given atom.
It is a region in insulators and semiconductors where no electron states exist. Although an electron may not exist in this region, it can “jump” across it under certain conditions. For insulators, the gap can be crossed only when breakdown conditions occur—as when a very high voltage is applied across the material. The band gap is illustrated
in Figure (a) for insulators. In semiconductors the band gap is very small, allowing an electron in the valence band to jump into the conduction band if it absorbs a photon. The band gap depends on the semiconductor material. This is illustrated in Figure (b). In conductors, the conduction band and valence band overlap, so there is no gap, as shown in Figure (c). This means that electrons in the valence band move easily into the conduction band, so there are always electrons available as free electrons. this is all about Conductor Insulator.