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A doped semiconductor has impurity level...

A doped semiconductor has impurity levels 30meV bleow the conduction band,(a)Is the material m-type or p-type? (b)In a thermal collision,and amount kT of energy is given to the extra electron loosely bound to the impurity ion and this electron is just able to jump into the conduction band. Calculate the temperature T.

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(a) The impurity provides impurity levels close to the conduction band and a number of electrons form the impurity level will populate the conduction band. Thus,the majority carriers are electrons and the meterial is n-type.
9According to the question,`kT=30meV`
or,`T=(30meV)/(k)`
`=0.03eV/8.62xx10^(-5)eVK_(-1)=348K.`
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Knowledge Check

  • The conductivity of intrinsic semiconductors can be increased by adding a suitable impurity. This process is called __(P)__. This can be done with an impurity which is __(Q)_ rich or deficient as compared to the semiconductor. Such impurities introduce __(R)__ defects in them. Electron rich impurities result in __(S)__ type semiconductors while electron deficit impurities result in __(T)___ type semiconductors .

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