Defect states which were introduced into float-zone material by heavy dopant diffusion were investigated by using the electron beam-induced current method. By measuring the minority carrier diffusion length, using the first-order moment method, and by directly imaging the defects, their electrical activity could be determined. The diffused samples were then dry-oxidized, so that changes in the electrical and morphological properties of the introduced defects could be monitored. Two sets of samples were investigated, one of which had been diffused with B and another which had been diffused with B and Al. Significant improvements in the diffusion length were observed in the samples into which Al had been co-diffused; thus providing evidence for an effect of Al upon the electrical activity of bulk defective states.

A.Castaldini, A.Cavallini, B.Fraboni, E.Giannotte: Journal of Applied Physics, 1992, 72[12], 5622-7