Radiation-Induced Electronic Defect Levels in High-Resistivity Si Detectors

摘要

Deep Level Transient Spectroscopy (DLTS) studies of 7-MeV proton induced deep levels have been performed in float-zone p~+-n~--n~+ Si detectors, where the n~- region is doped with phosphorous at ～3x10~(12) cm~(-3). The detectors have been produced from high-purity float zone Si with the concentration of C and O below 10~(16) cm~(-3). Dry and wet oxidation techniques and different heat treatments have been implemented in order to increase the concentration of O in the samples. Both majority and minority carrier DLTS measurements have been performed. The majority carrier DLTS spectra demonstrate presence of several dominating peaks assigned to vacancy-oxygen, divacancy and vacancy-phosphorous complexes, but no considerable difference in the level concentrations and in the peak ratios has been observed for the different samples. In all minority carrier DLTS spectra a dominating peak identified as a carbon-oxygen complex has been observed, and these spectra revealed considerable difference between the samples prepared with dry and wet oxidations. It has been found that another defect level, detected at lower temperatures and located at ～0.2 eV above the valence band edge, is present in the spectra for wet-oxidized samples. The dose dependence of the defect formation is found to be linear for doses ≤4x10 cm~(-2). Isochronal annealing studies show additional minor electron traps stable only up to temperatures ≤50℃.