ULTRASOUND STIMULATED DISSOCIATION OF FE-B PAIRS IN SILICON

We found that application of ultrasound vibrations to p-type silicon promotes a dissociation of iron-boron pairs. This effect is manifested by a decrease of the minority carrier diffusion length, L, after ultrasound treatment (UST) of the silicon wafer. Post-UST recovery of the diffusion length is identical after thermal and optical pair dissociation. This provides an unambiguous proof for dissociation of Fe-B pairs stimulated by ultrasound vibrations. The UST process creates interstitial iron donors which acts as efficient recombination centers and lower the L value. A relevant physical mechanism of the ultrasound effect is discussed. © 1995 American Institute of Physics.