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    Question

    The electrical conductivity of a semiconductor

    increases with rise in temperature because:
    A Ionization of impurity atoms increases Correct Answer Incorrect Answer
    B Recombination rate decreases Correct Answer Incorrect Answer
    C More covalent bonds are broken Correct Answer Incorrect Answer
    D Band gap decreases drastically Correct Answer Incorrect Answer

    Solution

    In a semiconductor , electrical conductivity depends on the number of free charge carriers (electrons and holes). As temperature rises, thermal energy increases , which causes more covalent bonds to break , liberating more electrons into the conduction band and creating holes in the valence band. This increase in intrinsic carrier concentration enhances conductivity. The band gap does decrease slightly with temperature, but not drastically enough to be the primary cause. The dominant mechanism is the thermal excitation of electrons across the band gap due to breaking of covalent bonds.

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