Laser-induced phase transitions in ion-implanted diamond

Abstract Results are reported on the study of phase transformations in D + (deuterium) ion-implanted diamond single crystals induced by nanosecond pulses of a KrF excimer laser (λ=248 nm). Multipulse laser irradiation at fluences lower than the graphitization thresholds resulted in progressive annealing, pronounced in an increase of the optical transmission and surface contraction. A non-linear defect distribution in a near-surface layer was found to strongly affect the annealing and graphitization processes; higher annealing efficiency and higher graphitization thresholds were observed under irradiation conditions when a laser beam was incident onto a buried defective layer through diamond, i.e., onto a ‘back’ side of the diamond sample opposite to the ion-implanted side. The influence of non-uniform laser-induced heating of defective diamond material on characteristic features of the phase transitions is discussed.