On the basis of the relative values of electrical conductivity(σ) and resistivity(ρ=1/σ), the solid are broadly classified as
They have very low resistivity or high conductivity.
Resistivity ρ ≈ 10⁻² – 10⁻⁸ Ωm and Conductivity σ = 10² – 10⁸ S/m (Siemens/metre)
They have high resistivity or low conductivity.
Resistivity ρ ≈ 10¹¹ – 10¹⁹ Ωm and Conductivity σ = 10⁻¹¹ – 10⁻¹⁹ S/m (Siemens/metre)
They have resistivity or conductivity intermediate to metals and insulators.
Resistivity ρ ≈ 10⁻⁵ – 10⁶ Ωm and Conductivity σ = 10⁵ – 10⁻⁶ S/m (Siemens/metre)
In this chapter we will study of Semiconductors, which can be following types.
(I) Element Semiconductors
These Semiconductors are available in natural form.
Exp – Silicon (Si) and Germanium (Ge)
(II) Compound Semiconductors
These semiconductors are made by compounding the metals.
Exp – (a) Inorganic Semiconductors are CDs, GaAs, CdSe, InP etc.
(b) Organic polymer are polypyrrole, polyaniline, etc.