Electrically Active Copper–Nickel Complexes in p-Type Silicon

The interaction of substitutional copper atoms (Cu_s) with interstitial nickel (Ni_i) or copper (Cu_i) in crystalline p-type Si is investigated by DLTS. The mobile interstitial species are introduced at near-room temperatures by etching in Ni- or Cu-contaminated KOH aqueous solutions. The Cu_i in-diffusion is confirmed by the formation of several deep level complexes including the photoluminescence Cu_PL center which is known to be a Cu_s atom decorated with three Cu_i species. The Ni_i in-diffusion results in the appearance of three novel electrically active Cu-Ni complexes; two of them are unstable at room temperature and transform into the third center which possesses a level at 0.16 eV above the top of the valence band. The deep-level depth profiles below the etched surface affirm that all three Cu-Ni complexes are formed on the base of one Cu_s atom by means of addition at least one Ni_i and one or more Cu_i species.