Al-Al pair in silicon: Evidence for long-range hydrogen-enhanced aluminum migration

In this letter, we present results of electron paramagnetic resonance studies of new defects (labeled Si-AA15 and Si-AA16) incorporated aluminum atoms. The AA15 defect is created in hydrogen-doped silicon by low temperature (similar to 80 K) irradiation, and an Al-27 (100% abundant, I = 5/2) hyperfine interaction reveals the presence of two nearly equivalent aluminum atoms. Therefore, the appearance of the AA15 defect containing Al-Al pair is the first observation of hydrogen-enhanced long-range migration (at least of similar to 100 lattice constants) of aluminum atom at low temperatures (<200 K). The AA15 center anneals out at room temperature. The AA16 center containing only one Al atom disappears at 200 K. Tentative models of AA15 and AA16 defects as an Al-Al [110]-split interstitial and Al-H interstitial pair correspondingly are proposed. (C) 1997 American Institute of Physics.