Question

Assume that the values of mobility of holes and that of electrons in an intrinsic semiconductor are equal and the values of conductivity and initrinsic electron density are 2.32 /Ω m and 2.5 × 10¹⁹ /m³ respectively. Then, the mobility of electron/hole is approximately:
1. 0.3 m²/Vs
2. 0.5 m²/Vs
3. 0.7 m²/Vs
4. 0.9 m²/Vs

Answer 1

Correct Answer - Option 1 : 0.3 m²/Vs

Concept:

Conductivity of intrinsic semiconductor is given by:

σ_r = n_i q (μ_n + μ_p)

Where, σ_i = intrinsic conductivity

q = electronic charge = 1.6 × 10^-19 C

μ_n = electron mobility

μ_p = hole mobility

n_i = Intrinsic carrier concentration

Calculation:

Given

σ_i = 2.32 /Ωm

n_i = 2.5 × 10¹⁹ / m³

q = 16 × 10^-19 C

μ_n = μ_p

Let μ_n = μ_p = μ

σ_i = n_i q (μ_n + μ_p)

2.32 = 2.5 × 10¹⁹ × 1.6 × 10^-19 (μ + μ)

2.32 = 2.5 × 1.6 × 2μ

μ = 0.29 m² / V-sec

μ ≃ 0.3 m² / V-sec