Long-range influence of weak optical irradiation of silicon

We report a new effect, observed experimentally in silicon under irradiation with visible-range light with a power density of 0.2–1.5 W/cm² for 8 s. The effect consists in an increase of microhardness on the side opposite to the irradiated side and is not purely thermal in character. After irradiation, the changes decrease exponentially with time with an activation energy of 0.75±0.05 eV, a value which is characteristic for the migration and reorientation of one of the types of intrinsic interstitial atoms. A qualitative explanation is given for the effect on the basis of a model previously proposed for the case of long-range influence of ion irradiation. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 6, 381–385 (25 September 1999)