GATE EC 2023 Set 1 — Question 61
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Electronic Devices → Semiconductor Physics → Equilibrium Carrier Concentration
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Question
In a semiconductor device, the Fermi-energy level is above the valence band energy. The effective density of states in the valence band at is . The thermal equilibrium hole concentration in silicon at is ____________ (rounded off to two decimal places).Given at is .
Correct answer
60 to 70
Solution
The hole concentration in a semiconductor is given by the formula:
Given parameters at :
Converting to the required units ():
The value to be filled is .
Given parameters at :
1.The effective density of states depends on temperature as :
2.The thermal energy scales linearly with temperature:
3.Calculating the hole concentration at (assuming the energy difference remains constant):
Converting to the required units ():
The value to be filled is .
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