Acoustic-wave-stimulated transformations of radiation defects in γ-irradiated n-type silicon crystals

The effect of an ultrasonic treatment (UST) in various regimes (fUST = 4−30 MHz; WUST = 0.1−2 W/cm2) on the electrical activity of radiation defects in γ-irradiated (D = 108 and 109 rad) n-type silicon crystals doped with oxygen (∼1018 and <5 × 1015 cm−3) has been studied. The energies and concentrations of the electrically active centers have been determined from an analysis of the temperature dependence (100−300 K) of the Hall effect characteristics, assuming a multilevel structure of these centers. The main types of the acoustically active defects, which change the properties of the semiconductor material upon UST, are the A-type centers (Ec − 0.20 eV) and divacancies (Ec − 0.26 eV) in Czochralski-grown single crystals and the divacancies and/or Ps−Ci complexes (Ec − 0.23 eV) in floating-zone-melted samples.