Effect of Dislocations on the Minority Carrier Lifetime in Semiconductors

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 10⁴-10⁷/cm² 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, σR=1N_Dτ (where ND=dislocationdensity, τ=lifetime). σR was found to decrease with increasing resistivity of germanium and was higher for silicon than for germanium of comparable purity.