Classification of Metals, Conductors and Semiconductors

On the basis of the relative values of electrical conductivity(σ) and resistivity(ρ=1/σ), the solid are broadly classified as

1. Metals

They have very low resistivity or high conductivity.

Resistivity ρ ≈ 10⁻² – 10⁻⁸ Ωm  and Conductivity σ = 10²  – 10⁸ S/m (Siemens/metre)

2. Insulators

They have high resistivity or low conductivity.

Resistivity ρ ≈ 10¹¹ – 10¹⁹ Ωm  and  Conductivity σ = 10⁻¹¹  – 10⁻¹⁹ S/m (Siemens/metre)

3. Semiconductors

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.

Also Read: CBSE Class 12 Physics Chapter-14 (Semiconductor and Electronic Devices) All Topics

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