Copper in silicon

The presence of Cu atoms in p-type Si is detected via their characteristic electric-field gradients measured at the radioactive acceptor ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$ ${/}^{111}$Cd by the perturbed γγ angular correlation technique. Cu forms pairs with acceptor atoms, thereby electrically passivating them, and is present as a contamination in Si wafers. Using the experimentally known Cu diffusion data and taking into account the effect of ion pairing, a new activation energy of 0.15 eV is deduced, which is in accordance with the dissociation energy of 0.70 eV measured for Coulombic-bound-acceptor–Cu pairs.