A method for determining energy-gap narrowing in n/+/ or p/+/ semiconductors

A general experimental method for the determination of the phenomenological energy-gap narrowing in regions of semiconductor devices that have high concentrations of donor or acceptor impurity atoms is presented. The theoretical grounds for the method are discussed, including the strong influence of Fermi-Dirac statistics on minority-carrier recombination in heavily doped regions. The method requires measurement only of the temperature dependence of dc current. The values of energy-gap narrowing are insensitive to the mechanisms controlling recombination and to the value of minority-carrier mobility in the heavily doped region; they are also independent of the value of the intrinsic carrier density, at a specific temperature. The measured values for the Si:As emitters of transistors and diodes studied are described by an empirical formula.