Depth progression of dissociation reaction of the 1.014-eV photoluminescence copper center in copper-diffused silicon crystal measured by deep-level transient spectroscopy

Changes in the concentration depth profiles of the 1.014-eV photoluminescence (PL) copper center and its dissociation product by annealing were measured by deep-level transient spectroscopy (DLTS). The transformation reaction between these centers by annealing was not homogeneous throughout; it started at the sample surface and extended deeper with increasing annealing time. From this finding, the precipitation of interstitial copper in the surface region and its out-diffusion in the bulk are analyzed as the underlying processes to dissociate the center. The origin of the difference in the dissociation energies of the center obtained by DLTS and PL measurements is discussed.