Question

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.

Answer 1

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

Step-by-step explanation:

The given data is as follows.

`N_(d) = 10^(19) per cm^(-3)`

`N_(a) = 10^(15) per cm^(-3)`

As we are given that
`n_(i)`exceeds impurity density by a factor of 10.

Therefore,
`n_(i) = 10N_(d)`

`10^(20) = 3.87 * 10^(6) * T^{(3)/(2)}e^({(-7014)/(T)})`

`T^{(3)/(2)}e^({(-7014)/(T)}) = (10^(20))/(3.87 * 10^(6))`

T = 1985 K

Also,
`n_(i) = 10N_(d)`

`10^(6) = 3.87 * 10^(16) * T^{(3)/(2)}e^({(-7014)/(T)})`

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.