The purpose of this paper was the investigation of a photostimulated m
odification of optical properties of semiconductors subsurface region,
to create elements and devices of integrated optics. The experiments
have been carried out in II-VI (CdS, CdTe) and III-V (GaAs) semiconduc
tor single crystals. It was shown that during the photostimulated proc
ess the enriching of cadmium occurs in the subsurface region of, e.g.,
CdS single crystals, and thus, the complex refractive index is strong
ly changed. For the first time this phenomenon was detected and invest
igated in CdS single crystals [1,2] and was named low temperature phot
o-hydromodification (LTPHM) method. In this paper the LTPHM-phenomenon
was shown to take place in GaAs and CdTe single crystals too. It was
theoretically shown that the subsurface region refractive index change
s take place due to an increase of clusters concentration, consisting
of interstitial atoms. Clusters change their forms during the LTPHM-pr
ocess.