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A semiconducting material has a band gap of 1 eV. Acceptor impurities are doped into it which create acceptor levels 1 me V above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if k T is more than twice the gap, the upper levels have maximum population. the temperature of the semiconductor is increased from 0 K. the concentration of the holes increases with temperature and after a certain temperature it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant. |
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Answer» A semiconducting material has a band gap of 1 eV. Acceptor impurities are doped into it which create acceptor levels 1 me V above the valence band. Assume that the transition from one energy level to the other is almost forbidden if kT is less than 1/50 of the energy gap. Also, if k T is more than twice the gap, the upper levels have maximum population. the temperature of the semiconductor is increased from 0 K. the concentration of the holes increases with temperature and after a certain temperature it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant. |
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