JEE Main & Advanced Physics Semiconducting Devices Question Bank Critical Thinking

  • question_answer
    A silicon speciman is made into a P-type semi-conductor by dopping, on an average, one Indium atom per \[5\times {{10}^{7}}\]silicon atoms. If the number density of atoms in the silicon specimen is \[5\times {{10}^{28}}\text{atoms}/{{m}^{3}}\] then the number of acceptor atoms in silicon per cubic centimetre will be [MP PMT 1993, 2003]

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

    B)            \[1.0\times {{10}^{13}}atoms/c{{m}^{3}}\]

    C)            \[1.0\times {{10}^{15}}atoms/c{{m}^{3}}\]                

    D)            \[2.5\times {{10}^{36}}atoms/c{{m}^{3}}\]

    Correct Answer: C

    Solution :

                       Number density of atoms in silicon specimen = 5 ´ 1028 atom/m3 = 5 ´ 1022 atom/cm3                              Since one atom of indium is doped in 5 ´ 107 Si atom. So number of indium atoms doped per cm3 of silicon.                    \[n=\frac{5\times {{10}^{22}}}{5\times {{10}^{7}}}=1\times {{10}^{15}}\,atom/c{{m}^{3}}.\]


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