Deep-level transient spectroscopy and photoluminescence measurements of dissociation energy of the 1.014-eV copper center in copper-diffused silicon crystal

Abstract

Dissociation of the 1.014-eV copper center by annealing in a silicon crystal diffused with dilute copper was measured by deep-level transient spectroscopy (DLTS) and photoluminescence (PL) methods. Clearly different dissociation energies were obtained from the dissociation lifetimes of the center measured by the two methods: 1.01 eV by DLTS and 0.60 eV by PL. On the basis of the previously reported analysis that the precipitation of interstitial copper (Cui) at the surface and the subsequent out-diffusion of Cui in the bulk are the underlying processes to dissociate the center by annealing, we assumed that the difference in the aforementioned dissociation energies originates from the difference in the influence of the underlying processes at different depths in addition to the difference in the detection depths of both methods (PL: ≥ 30 μm and DLTS: ≈ 3 μm). Using the dissociation energies obtained in this study, together with the reported diffusion barrier of Cui, we estimated the binding energy of the center as lower than 0.42 eV and the precipitation barrier of Cui as higher than 0.41 eV. This binding energy is low enough to support the presence of weak bonding in the copper center reported in previous researches.