Effect of Dislocations on the Minority Carrier Lifetime in Semiconductors

Abstract

The density of random dislocations in germanium and silicon crystals has been measured by means of x-ray rocking curves and by etch pit counting. Data obtained by the two methods are in good agreement, and dislocation densities in the range ${10}^4$-${10}^7$/${\mathrm{cm}}^2$ were found. The minority carrier lifetime was shown to vary with the dislocation density, and the results could be expressed in terms of a recombination efficiency per unit length of dislocation line, ${\sigma }_R=\frac{1}{N_{D\tau }}$ (where $N_D=\mathrm{dislocation}\mathrm{density}$, $\tau =\mathrm{lifetime}$). ${\sigma }_R$ was found to decrease with increasing resistivity of germanium and was higher for silicon than for germanium of comparable purity.