Engineering Physics

Solved Problems

1.    Find the resistivity of an intrinsic semiconductor with intrinsic concentration of 2.5 × 10¹⁹ per m³. The mobilities of electrons and holes are 0.40 m²/ V-s and 0.20 m²/ V-s.

Sol: Given data are:

Intrinsic concentration (n_i) = 2.5 × 10¹⁹/m³

Mobility of electrons (μ_n) = 0.40 m²/V-s

The mobility of holes (μ_p) = 0.20 m²/V-s

The conductivity of an intrinsic semiconductor (σ_i) = n_ie[μ_n + μ_p]

2.    Calculate the number of donor atoms per m³ of n-type material having resistivity of 0.25 Ω-m, the mobility of electrons is 0.3 m²/V-s.

Sol: We know:

[Since n = number of free electron per m³ ≈ number of donor atoms in n-type]

3.    At ...