Evaluation of hole traps in 10-MeV proton-irradiated p-type silicon from Hall-effect measurements

Using the temperature dependence of the hole concentration p(T) obtained fr om Hall-effect measurements. we attempt to uniquely determine the densities and energy levels of hole traps in 10-MeV proton-irradiated p-type silicon . Since the function p(T)exp(E-ref/kT)/kT has a peak at the temperature cor responding to each hole trap level, the trap densities and energy levels ca n be determined uniquely and accurately. Here, k is the Boltzmann's constan t, T is the absolute temperature and E-ref is a newly introduced parameter which shifts the peak temperature of the function within the measurement te mperature range. Three types of hole trap levels (about 0.09 eV, 0.13 eV an d 0.19 eV above the top (E-v) of the valence band) are observed, and these hole trap densities increase with increasing 10-MeV-proton fluence. The hol e traps at E-v + 0.09 cV and E-v + 0.19 eV have been reported and their ori gins have been discussed. However; the hole trap at E-v + 0.13 eV has not y et been reported. The quantitative relationship between the decrease in hol e concentration and the increase in densities of certain traps due to proto n irradiation has been clarified for the first time.