CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    A silicon specimen is made into a p-type semiconductor by doping, on an average, one indium atom per\[5\times {{10}^{7}}\]silicon atoms. If the number density of atoms in the silicon specimen is\[5\times {{10}^{28}}atom/{{m}^{3}},\]then the number of acceptor atoms in silicon per cubic centi metre will be:

    A)  \[2.5\times {{10}^{30}}atom/c{{m}^{3}}\]

    B)  \[2.5\times {{10}^{35}}atom/c{{m}^{3}}\]

    C)  \[1\times {{10}^{13}}atom/c{{m}^{3}}\]

    D)  \[1\times {{10}^{15}}atom/c{{m}^{3}}\]

    E)  none of the above

    Correct Answer: D

    Solution :

    Number density of atoms in silicon specimen \[=5\times {{10}^{28}}atoms/{{m}^{3}}=5\times {{10}^{22}}atoms/c{{m}^{3}}\]. Since, 1 atom of indium is doped in\[5\times {{10}^{7}}\]silicon atoms, so total number of indium atoms doped per\[c{{m}^{3}}\]of silicon will be \[n=\frac{5\times {{10}^{22}}}{5\times {{10}^{7}}}={{10}^{15}}atoms/c{{m}^{3}}\]


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