LOW-FLUENCE EXCIMER-LASER IRRADIATION-INDUCED DEFECT FORMATION IN INDIUM-TIN OXIDE-FILMS

DC sputtered indium-tin oxide (ITO) films of 500 nm thickness are irra diated with single pulses of fluences between 190 and 510 mJ/cm(2) fro m a KrF excimer laser. The irradiation induced changes in optical spec tra are consistently described through the behaviour of four (Gaussian -like) absorption bands at 0.7, 1.0, 1.6 and 2.6 eV. Being absent in t he original films and emerging at fluences exceeding 300 mJ/cm(2), the 2.6 eV contribution is most characteristic to excimer laser processin g. X-ray photoelectron spectroscopic analysis suggests that the irradi ation-induced changes should be associated with oxygen displacement wi thin the atomic network rather than surface reduction via oxygen remov al, Thermal model calculations reveal that the principal effect of sin gle pulse processing in this fluence domain is deep melting of the fil ms. Defects created during molten phase resolidification are assumed t o be responsible for the irradiation-induced changes in the short rang e chemical structure of the films.