INTERACTION OF IRON WITH TRANSITION-METALS AND ALPHA-RADIATION IN THERMALLY QUENCHED P-SILICON

Iron-induced deep levels have been studied in p-type silicon quenched from high temperatures, using deep-level transient spectroscopy. The i nterstitial iron donor and the iron-boron pair defect are observed and identified by a number of their characteristics including their mutua l transformation. Our recent work revealed an interesting new property of the interstitial iron donor defect, namely its complete bleaching by the transition metals Ag, Au, Pt and Pd in samples which have recei ved thermal treatment identical to the undoped samples. The study repo rted here was intended to investigate the relationship of this effect to the well known iron-boron complex defect known to act as a source o f the interstitial iron defect by injection-induced dissociation in bo ron doped p-silicon. Our results show that both the iron-boron complex and the isolated interstitial iron defects disappear concurrently in our transition-metal-doped samples. Thus the bleaching of the iron int erstitial in the presence of the transition metals used is found to be associated with the bleaching of this source rather than due to some unknown complex mechanism inhibiting the dissociation of these pairs i n the presence of the transition metals. In addition, the response of the iron interstitial defect to irradiation with alpha-particles and i ts thermal annealing behaviour have been studied. Alpha-irradiation is seen to lead to a significant suppression of the iron interstitial de fect, in agreement with the hitherto reported results of electron irra diation, without causing any significant change in its thermal anneali ng characteristics.