PN junction — UPSC Physics Optional CSE 1986 Paper II

Explain, on the basis of bond structure, the behaviour of insulators and conductors. Describe the effect of adding donor or acceptor impurities on conduction in a semi-conductor. Explain the action of a p-n junction as a rectifier. \begin{aligned} \text{Mass of electron} &= 9.1 \times 10^{-31}\text{ kg} \\\\ 1\text{ a.m.u} &= 931\text{ MeV} \\\\ \text{Avogadro's numbers} &= 6.1 \times 10^{23}\text{ (gm-mole)}^{-1} \\\\ \varepsilon_0 &= 1/36\pi \times 10^{-9}\text{ f/m} \\\\ h &= 6.6 \times 10^{-27}\text{ erg sec} \\\\ c &= 3.0 \times 10^{10}\text{ cm/sec} \\\\ 1\text{ eV} &= 1.6 \times 10^{-19}\text{ erg} \\\\ &= 1.6 \times 10^{-19}\text{ joule} \end{aligned}