1
GATE ECE 2025
MCQ (Single Correct Answer)
+2
-0.67
The intrinsic carrier concentration of a semiconductor is $2.5 \times 10^{16} / \mathrm{m}^3$ at 300 K . If the electron and hole mobilities are $0.15 \mathrm{~m}^2 / \mathrm{Vs}$ and $0.05 \mathrm{~m}^2 / \mathrm{Vs}$, respectively, then the intrinsic resistivity of the semiconductor (in $\mathrm{k} \Omega . \mathrm{m}$ ) at 300 K is _________ (Charge of an electron $e=1.6 \times 10^{-19} \mathrm{C}$.)
A
1.65
B
1.25
C
0.85
D
1.95
2
GATE ECE 2025
MCQ (Single Correct Answer)
+2
-0.67

The electron mobility $\mu_n$ in a non-degenerate germanium semiconductor at 300 K is $0.38 \mathrm{~m}^2 / \mathrm{Vs}$.

The electron diffusivity $D_n$ at 300 K (in $\mathrm{cm}^2 / \mathrm{s}$, rounded off to the nearest integer) is ____________

(Consider the Boltzmann constant $k_B=1.38 \times 10^{-23} \mathrm{~J} / \mathrm{K}$ and the charge of an electron $e=1.6 \times 10^{-19} \mathrm{C}$.)

A
26
B
98
C
38
D
10
3
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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4
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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