A method and a structure for reducing defects in buried oxide layers of a silicon-on-insulator substrate. The method includes: generating a beam of infrared radiation of a selected wavelength; exposing a silicon-on-insulator substrate to the beam of infrared radiation, the substrate comprising a buried silicon dioxide layer between a lower layer of silicon and an upper layer of silicon; and wherein silicon has a transmittance of at least 95% at the selected wavelength and silicon dioxide has a transmittance of less than 80% at the selected wavelength.