Electronic Devices Question 248
Question: The contribution in the total current flowing through a semiconductor due to electrons and holes are $ \frac{3}{4} $ and $ \frac{1}{4} $ respectively. If the drift velocity of electrons is $ \frac{5}{2} $ times that of holes at this temperature, then the ratio of concentration of electrons and holes is
Options:
A) 6 : 5
B) 5 : 6
C) 3 : 2
D) 2 : 3
Show Answer
Answer:
Correct Answer: A
Solution:
As we know current density J = nqv
Therefore $ J _{e}=n _{e}qv _{e} $ and $ J _{h}=n _{h}qv _{h} $
Therefore $ \frac{J _{e}}{J _{h}}=\frac{n _{e}}{n _{h}}\times \frac{v _{e}}{v _{h}} $
Therefore $ \frac{3/4}{1/4}=\frac{n _{e}}{n _{h}}\times \frac{5}{20} $
Therefore $ \frac{n _{e}}{n _{h}}=\frac{6}{5} $
