A pure semiconductor has equal electron and hole concentration of $6 imes10^{8}\ ext{m}^{-3}$. After doping with a suitable impurity the electron concentration rises to $9 imes10^{12}\ ext{m}^{-3}$.
(i) What type of extrinsic semiconductor is formed after doping?
(ii) Calcu

Question

A pure semiconductor has equal electron and hole concentration of $6	imes10^{8}\ 	ext{m}^{-3}$. After doping with a suitable impurity the electron concentration rises to $9	imes10^{12}\ 	ext{m}^{-3}$.
(i) What type of extrinsic semiconductor is formed after doping?
(ii) Calculate new concentration of holes.

Accepted Answer

>

> [!TLDR]
> Electron concentration rose, so it's n-type; use the mass-action law n_e n_h = n_i^2 for the new hole concentration.
>
> (i) Since doping raised the **electron** concentration (majority carriers = electrons), the extrinsic semiconductor formed is **n-type**.
>
> (ii) By the law of mass action, $n_e n_h=n_i^2$, where $n_i=6	imes10^{8}	ext{ m}^{-3}$ is the original (intrinsic) concentration.
>
> $n_i^2=(6	imes10^{8})^2=3.6	imes10^{17}	ext{ m}^{-6}$.
> …

Q.A pure semiconductor has equal electron and hole concentration of $6\times10^{8}\ \text{m}^{-3}$ . After doping with a suitable impurity the electron concentration rises to $9\times10^{12}\ \text{m}^{-3}$ .

Concept understanding — Extrinsic Semiconductor (Doping)

Q.A pure semiconductor has equal electron and hole concentration of 6×108 m−36\times10^{8}\ \text{m}^{-3}6×108 m−3. After doping with a suitable impurity the electron concentration rises to 9×1012 m−39\times10^{12}\ \text{m}^{-3}9×1012 m−3.

Concept understanding — Extrinsic Semiconductor (Doping)

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Q.A pure semiconductor has equal electron and hole concentration of $6\times10^{8}\ \text{m}^{-3}$ . After doping with a suitable impurity the electron concentration rises to $9\times10^{12}\ \text{m}^{-3}$ .

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