NEET PHYSICS by Pradeep kshetrapal
Semiconductor Lesson no. NEET-PHY-9-01
A semiconductor having electron and hole mobilities and Ho respectively. If its intrinsic carrier density is n, then what will be the value of hole concentration P for which the conductivity will be minimum at a given temperature? a) niVi. (c) nivHp un p /
In this question the quantity to be calculated is conductivit, and the other involved quantities are mobility of electron, number density of electrons and holes etc. So relation suggested is conductivity due to negative electron is -nneun where n is concentration of electrons e is charge on electron, Hn is mobility of electron. Similarly conductivity of hole 157 npe p
Further hole concentration np has a relation 2 For minimum conductivity ( 0)
Hence conductivity of semiconductor is The minimum value of conductivity is zero 2 pepp mp Multiplying with np and dividing by e on both sides 2 2
2 2 2 2 Hence right option is (a)
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