A silicon wafer is n‑type with donor concentration $N_D=2\times 10^{16}{\text{cm}}^{-3}$ and electron mobility ${\mu }_n=1500{\text{cm}}^2{\text{V}}^{-1}{\text{s}}^{-1}$. Assuming holes are negligible, calculate the electrical conductivity $\sigma$ of the wafer in ${\Omega }^{-1}{\text{cm}}^{-1}$. (Take $q=1.6\times 10^{-19}\text{C}$)

Step-by-step solution

1. Write the expression for conductivity: $\sigma =qn\mu$, where $n\approx N_D$ for an n‑type wafer.
2. Substitute the given values: $\sigma =(1.6\times 10^{-19})(2\times 10^{16})(1500)$.
3. Multiply $2\times 10^{16}$ by $1500$ to get $3\times 10^{19}$.
4. Now multiply by $1.6\times 10^{-19}$: $\sigma =1.6\times 10^{-19}\times 3\times 10^{19}=4.8$.
5. State the result with correct units.

Concept tested: Conductivity of doped semiconductor

Published 20 September 2026 · How this solution was prepared and checked