Optical properties of silicon with a high content of boron

After exposure of silicon with a high content of boron and oxygen to light with the spectrum close to that of solar radiation and with the intensity 70–80 mW cm$^{-2}$, a new defect corresponding to the absorption band observed at liquid-helium temperature at the frequency 1026.7 cm$^{-1}$ is detected in the material. It is shown that the components of the defect are boron and oxygen atoms. The defect is formed at a considerable concentration of free charge carriers induced by exposure of the sample to light or by heat treatments at a low current flow through the sample. It is thought that the defect can be formed due to the direct interaction between the components as well as via the precursors of the stable form of the defect. It is shown that doping of silicon with germanium reduces the efficiency of the formation of the defect corresponding to the detected absorption band.