Question

How many extra free electrons does the addition of \[0.001\%\] arsenic donate in \[1\ \mathrm{cm^3}\] of germanium?

Options

• \[10^{22}\] extra free electrons

• \[10^{17}\] extra free electrons

• \[10^{4}\] extra free electrons

• \[2.5\times10^{13}\] extra free electrons

Answer 1

Adding \[0.001\%\] arsenic donates \[10^{17}\] extra free electrons in the same volume. This greatly increases the free-electron count compared with pure germanium.