Q10Electrical Materials
Question
2 marks
Q.10. The intrinsic semiconductor carrier density is 1.5×10¹⁶ m⁻³. If the mobility of electron and holes are 0.13 and 0.05 m²V⁻¹s⁻¹, calculate the conductivity.
Answer
Using σ = ni·e·(μe + μh) with ni = 1.5×10¹⁶ m⁻³, μe = 0.13 and μh = 0.05 m²V⁻¹s⁻¹: σ = 1.5×10¹⁶ × 1.6×10⁻¹⁹ × 0.18 = 4.32×10⁻⁴ S/m.
For an intrinsic semiconductor, electrons and holes are present in equal concentration ni, and both contribute to conduction:
The conductivity of the intrinsic semiconductor is therefore 4.32×10⁻⁴ S/m (equivalently, resistivity ρ = 1/σ ≈ 2315 Ω·m), illustrating the characteristically low conductivity of intrinsic material compared to doped semiconductors or metals.