Positron spectroscopy of defects

For the first time a photopositron effect of a considerable increase in positronium (Ps) atom yield was observed in n- and p-Si monocrystals during the crystal irradiation with light. The method of angular distribution of annihilation photons was used. Photon spectra have been measured in the range of angles from -4 to +4 mrad on the p- and n-Si (110) crystals. It is found that there is a narrow component in spectra at room temperature, at that, the area under it increases when enhancing the light source power and predominantly in the region of infrared radiation. It is shown that the effect may be used for the defect spectroscopy in crystals