Observation of low-temperature diffusion of aluminum impurity atoms in hydrogen-implanted silicon

Single-crystal samples of aluminum-doped silicon implanted with hydrogen at similar to 80 K were examined by electron spin resonance (ESR). Two new ESR spectra labeled Si-AA15 and Si-AA16 were observed. The hyperfine structure of the spectra unambiguously reveals that two aluminum atoms and one aluminum atom are incorporated in the AA15 and AA16 defects, respectively. Observation of Al-Al pairs (the AA15 defect) is evidence in favor of long-range migration of aluminum atoms. The migration occurring in the experiment at T less than or equal to 200 K cannot be normal or recombination-enhanced (injection-enhanced) diffusion. Tentative models including Al-Al interstitial pairs as well as a hydrogen-enhanced migration mechanism are discussed. (C) 1998 American Institute of Physics.