EPR studies of heat-treatment centers inp-type silicon

The influence of acceptor doping (B,Al,Ga,In) on heat-treatment (HT) centers in oxygen-rich silicon was studied by means of EPR and resistivity measurements. EPR studies revealed that spectra Si-NL8 and Si-NL10 were practically the only ones which could be related to HT centers. They could be observed in all samples regardless of their acceptor doping. The creation of NL8 was found to depend on the initial acceptor concentration. For the aluminum-doped material the production of NL10 HT centers was particularly enhanced. No hyperfine structure of either NL8 or NL10 was found in EPR for specimens whose oxygen content was enriched to 46% in the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ isotope. Thermal donor (TD) concentrations, as found from the resistivity measurements, did not follow the relations predicted by the existing descriptions of TD formation. For all the studied samples concentrations of TD’s and NL10 centers were of the same order of magnitude.