Electrically Active Copper–Nickel Complexes in p‐Type Silicon

The interaction of substitutional copper atoms (Cus) with interstitial nickel (Nii) or copper (Cui) 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 Cui in‐diffusion is confirmed by the formation of several deep level complexes including the photoluminescence CuPL center which is known to be a Cus atom decorated with three Cui species. The Nii 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 Cus atom by means of addition at least one Nii and one or more Cui species. The interaction of highly mobile transition metal ions with substitutional impurities in Si at around room temperatures is of major concern in device technology. The fundamental aspect of this work is related to the question of how precipitate formation starts. The binding of fast diffusing Ni and Cu interstitials with substitutional Cu in Si is chosen to learn about the defect reactions.