PROBLEMS CONCERNING SPATIAL DISTRIBUTION OF DEEP IMPURITIES IN SEMICONDUCTORS

Variation in the spatial distribution of recombination centres within a semiconductor causes difficulties in the interpretation of lifetime measurements. These difficulties are assessed for three methods of lifetime assessment; photoconductive decay, charge storage and diode reverse leakage current. A quantitative comparison of these methods is made on the basis of the simple model of a semiconductor consisting of a matrix of low recombination centre concentration containing embedded volumes of a much higher concentration. Under these conditions it is shown that the diode reverse leakage current is the most meaningful method of estimating the average recombination centre concentration. The charge storage method is seriously affected by clustering of recombination centres and the analysis shows how this method can be used to estimate qualitatively that clustering is present. © 1969.