1
GATE ECE 2024
Numerical
+2
-0

A non-degenerate n-type semiconductor has 5 % neutral dopant atoms. Its Fermi level is located at 0.25 eV below the conduction band ($E_C$) and the donor energy level ($E_D$) has a degeneracy of 2. Assuming the thermal voltage to be 20 mV, the difference between $E_C$ and $E_D$ (in eV, rounded off to two decimal places) is _______.

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2
GATE ECE 2023
Numerical
+2
-0

In an extrinsic semiconductor, the hole concentration is given to be 1.5$$n_i$$ where $$n_i$$ is the intrinsic carrier concentration of 1 $$\times$$ 10$$^{10}$$ $$cm^{-3}$$. The ratio of electron to hole mobility for equal hole and electron drift current is given as ___________ (rounded off to two decimal places).

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3
GATE ECE 2023
Numerical
+2
-0

In a semiconductor device, the Fermi-energy level is 0.35 eV above the valence band energy. The effective density of states in the valence band at T = 300 K is 1 $$\times$$ 10$$^{19}$$ cm$$^{-3}$$. The thermal equilibrium hole concentration in silicon at 400 K is _____________ $$\times$$ 10$$^{13}$$ cm$$^{-3}$$ (rounded off to two decimal places).

Given kT at 300 K is 0.026 eV.

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4
GATE ECE 2022
MCQ (More than One Correct Answer)
+2
-0

Select the CORRECT statements regarding semiconductor devices

A
Electrons and holes are of equal density in an intrinsic semiconductor at equilibrium.
B
Collector region is generally more heavily doped than Base region in a BJT.
C
Total current is spatially constant in a two terminal electronic device in dark under steady state condition.
D
Mobility of electrons always increases with temperature in Silicon beyond 300 K.
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