1
GATE ECE 2023
MCQ (Single Correct Answer)
+1
-0.33

In a semiconductor, if the Fermi energy level lies in the conduction band, then the semiconductor is known as

A
degenerate n-type.
B
degenerate p-type.
C
non-degenerate n-type.
D
non-degenerate p-type.
2
GATE ECE 2023
MCQ (Single Correct Answer)
+1
-0.33

For an intrinsic semiconductor at temperature $$T=0K$$, which of the following statement is true?

A
All energy states in the valence band are filled with electrons and all energy states in the conduction band are empty of electrons.
B
All energy states in the valence band are empty of electrons and all energy states in the conduction band are filled with electrons.
C
All energy states in the valence and conduction band are filled with holes.
D
All energy states in the valence and conduction band are filled with electrons.
3
GATE ECE 2022
MCQ (Single Correct Answer)
+1
-0.33

Consider a long rectangular bar of direct bandgap p-type semiconductor. The equilibrium hole density is 1017 cm$$-$$3 and the intrinsic carrier concentration is 1010 cm$$-$$3. Electron and hole diffusion lengthss are 2 $$\mu$$m and 1 $$\mu$$m, respectively. The left side of the bar (x = 0) is uniformly illuminated with a laser having photon energy greater than the bandgap of the semiconductor. Excess electron-hole pairs are generated ONLY at x = 0 because of the laser. The steady state electron density at x = 0 is 1014 cm$$-$$3 due to laser illumination. Under these conditions and ignoring electric field, the closest approximation (among the given options) of the steady state electron density at x = 2 $$\mu$$m, is _____________.

A
0.37 $$\times$$ 1014 cm$$-$$3
B
0.63 $$\times$$ 1013 cm$$-$$3
C
3.7 $$\times$$ 1014 cm$$-$$3
D
103 cm$$-$$3
4
GATE ECE 2022
MCQ (Single Correct Answer)
+1
-0.33

In a non-degenerate bulk semiconductor with electron density n = 1016 cm$$-$$3, the value of EC $$-$$ EFn = 200 meV, where EC and EFn denote the bottom of the conduction band energy and electron Fermi level energy, respectively. Assume thermal voltage as 26 meV and the intrinsic carrier concentration is 1010 cm$$-$$3. For n = 0.5 $$\times$$ 1016 cm$$-$$3, the closest approximation of the value of (EC $$-$$ EFn), among the given options is _________.

A
226 meV
B
174 meV
C
218 meV
D
182 meV
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