STANDARDPhysics-Semiconductors
STANDARD Physics Doping in Semiconductors MCQ Question
Type: MCQ-numerical-Medium
Pure Si at 500 K has equal number of electron (nₑ) and hole (nₕ) concentrations of 1.5 × 10¹⁶ m⁻³. Doping by indium increases nₕ to 4.5 × 10²² m⁻³. The doped semiconductor is of
A
n-type with electron concentration nₑ = 2.5 × 10²³ m⁻³
B
p-type having electron concentration nₑ = 5 × 10⁹ m⁻³
C
n-type with electron concentration nₑ = 5 × 10²² m⁻³
D
p-type with electron concentration nₑ = 2.5 × 10¹⁰ m⁻³
Correct Answer
Option B
Detailed Explanation
Here, nᵢ = 1.5 × 10¹⁶ m⁻³, nₕ = 4.5 × 10²² m⁻³. As nₑnₕ = nᵢ², nₑ = (nᵢ² / nₕ) = (1.5 × 10¹⁶ m⁻³)² / 4.5 × 10²² m⁻³ = 5 × 10⁹ m⁻³, indicating a p-type semiconductor.
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