Conductivity of a Semiconductor

       The Ohm's law for the conduction current states that,

                   J = σ  E   where σ  = Conductivity

       While the total drift current density of a semiconductor is given by,

                   J = J_n + J_p = (n μ_n +p μ_p) q E

       Thus comparing the two equations, the conductivity of a semiconductor is given by,

                   σ  = (n μ_n + p μ_p) q (Ω-m)^-1

       This is general expression of the conductivity of a semiconductor. From this, conductivity of intrinsic and extrinsic semiconductors can be obtained.

       Thus the conductivity of a semiconductor depends on,

i) The concentration of electrons and holes i.e. n and p.

ii) The mobilities of electron and hole i.e. μ_n and μ_p.

iii) The charge on one electron i.e. q.

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