Effect of Impurity Conduction on Electron Recombination in Germanium and Silicon at Low Temperatures

Abstract

There is given a prediction concerning the effect of impurity conduction on the electron-donor recombination cross section in $n$-type Ge and Si at liquid-helium temperatures. The theory suggests that the capture probability of a conduction electron and an ionized donor becomes independent of temperature below a certain critical temperature $T_c$, where $T_c$ is primarily a function of the donor concentration. This proposed effect has been observed only in a single instance; in others, the experiments either were performed at insufficiently low temperatures or had inherent defects which tended to make a comparison of the theory with experiment somewhat difficult. In the latter cases, suggestions are offered to offset these difficulties. The various theories of electron recombination are contrasted; in particular, the classical theory of Hamann and McWhorter is shown to contain a number of serious deficiencies.