The basic problems of the receiving p-n junctions in ion implanted InSb Mg / after CO 2 -laser irradiation and in
InSb pand InAs pafter Ruby laser irradiation are represented. Proper Volt-Ampere characteristics are analyzed. The basic physical mechanisms of receiving these structures are discussed too. Basic cause of difference these p-n junctions is various mechanisms of irreversible interaction light and semiconductor (self-absorption for Ruby laser irradiation and "damage"-absorption for CO 2 -laser irradiation).