2. An N-type sample of silicon has uniform density (Nd = 1019/cm–3 ) of arsenic, and a P-type silicon sample has a uniform density (Na = 1015 /cm–3 ) of boron. For each sample, determine the following: (a) The temperature at which the intrinsic concentration ni exceeds the impurity density by factor of 10.

Respuesta :

Answer: The temperature at which the intrinsic concentration exceeds the impurity density by factor of 10 is 636 K.

Explanation:

The given data is as follows.

         [tex]N_{d} = 10^{19} per cm^{-3}[/tex]

         [tex]N_{a} = 10^{15} per cm^{-3}[/tex]

As we are given that [tex]n_{i}[/tex]exceeds impurity density by a factor of 10.

Therefore,   [tex]n_{i} = 10N_{d}[/tex]

   [tex]10^{20} = 3.87 \times 10^{6} \times T^{\frac{3}{2}}e^({\frac{-7014}{T}})[/tex]

[tex]T^{\frac{3}{2}}e^({\frac{-7014}{T}}) = \frac{10^{20}}{3.87 \times 10^{6}}[/tex]

          T = 1985 K

Also,  [tex]n_{i} = 10N_{d}[/tex]

       [tex]10^{6} = 3.87 \times 10^{16} \times T^{\frac{3}{2}}e^({\frac{-7014}{T}})[/tex]

                T = 636 K

Thus, we can conclude that the temperature at which the intrinsic concentration exceeds the impurity density by factor of 10 is 636 K.

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