Effect of high-pressure high-temperature treatment on neutron-irradiation-induced defects in Czochralski silicon

Czochralski-grown silicon crystals of the same initial oxygen content were subjected to various high temperature- high pressure (HTHP) treatments for different time durations. Subsequently, the crystals were irradiated by fast neutrons at approximately 50 degrees C. One of the main defects form is VO pair usually identified in the IR spectra by the 830 cm-1 localized vibrational model (LVM) band. Upon annealing, this defect is converted to the VO2 defect responsible for a LVM band at 887 cm-1. The purpose of this work is to study the effect of various combinations of HTHP treatment prior to irradiation on the annealing behavior of the VO defect and particularly on its conversion to the VO2 defect. We have concluded that the conversion of VO to VO2 depend on the forms of oxygen impurity and on other defects created in the sample after the HTHP treatment, as for example dislocations and stacking faults.