ELEC2133 Lecture Notes - Lecture 2: Electric Field, Indium, Drift Current
21 Aug 2018
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Document Summary
Key concepts: intrinsic (pure) semiconductors: ( ) electroncs & (+) holes for e. g. si group iv, extrinsic (doped) semiconductors, n doped => mobile ( , p doped => mobile (+) e. g. p, as group v, p doped => mobile (+) e. g. p, as group v e. g. b, ga group iii, p n junction => diode. Extrinsic (doped) semiconductors contain small amounts of impurities. Donor impurities the fifth electron is weakly bound to the donor impurity, i. e. only a small energy is needed to move the electron in to the cb. Acceptor impurities a valence band electron is accepted by the impurity leaving a weakly bound vb hole, i. e. only a small energy is needed to move this hole into the vb. When n type and p type semiconductors are brought together, they form a pn junction. To start with, we will consider the case at thermal equilibrium, where there is no applied voltage bias or light or temperature.
