Electrically Active Copper–Nickel Complexes in p‐Type Silicon

Abstract

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.

Electrical Activation of Interstitial Ni in Cu‐Doped Si

“…[15] Similarly, Ni s decorated with some other atoms could have donor and acceptor levels close to those of isolated Ni s but no second acceptor level. This hypothesis is in agreement with the observation that the H 80 and E 236 centers are formed not directly but through the intermediate stages, Cu-Ni 160 [7] and E 217 complexes (Figure 3), respectively. In both cases, the sum total of all centers was equal to the initial Cu s concentration.…”

“…Emission rates from the H 80 center were measured on the samples used in our previous work where the H 80 level was denoted as Cu-Ni 80 . [7] Yet, only weak traces of the Cu 145 and Cu 185 centers were found after KOH:Ni treatment. These defects were located in the near-surface layer after the CP4 etching and were etched out by the long-term KOH:Ni treatment at a rather high temperature (60 °C, 40 min).…”

“…Emission rates from the center were measured on the samples used in our previous work where the level was denoted as Cu–Ni 80 . [ 7 ]…”

“…Introduction of the species into p‐type ‐doped Si crystals results in a partial transformation of substitutional copper into the center with deep‐level transient spectroscopy (DLTS) signature very similar to the donor level. [ 7 ] However, the direct replacing of with is unexpected as the copper‐vacancy binding energy was calculated to exceed the energy gain from the – V reaction. [ 8,9 ] To gain further insights into the possibility of the Cu−Ni exchange reaction, we extend the experiments to n‐type ‐doped crystals, where the reaction could be monitored by the formation of substitutional acceptor levels.…”

Nickel Interaction with Vacancy‐Type Radiation Defects in Silicon

“…Nickel is known to be detrimental to silicon‐based electronic devices because of the extremely high diffusivity and many possible sources of nickel contamination . Recently, we showed that nickel can penetrate into silicon even at room temperatures and form complexes with radiation defects . In particular, nickel interaction with the vacancy–oxygen pair ( V O, A‐center) resulted in formation of the Ni V O complex with an acceptor level at 0.37 eV below the bottom of the conduction band.…”