Ablation of Single Crystal MgO by UV Excimer Irradiation

Abstract

AbstractThe ablation of single crystal MgO irradiated with 248 nm excimer laser light is studied by means of time resolved spectroscopy and quadrupole mass spectrometry. Luminescence spectra and SEM observations indicate that repeated laser bombardment gradually increases the density of potentially absorbing defects. In polished samples, this progressive growth is preceded by an initial clean-up (reduction) of surface damage. Unlike many wide band gap materials, defect production in MgO by electronic mechanisms is not likely. Chemical etch techniques indicate the presence of high dislocation densities in regions etched by the laser, suggesting that point defect production by dislocation motion is important. The ablation plume is composed of charged particles, including cluster ions, as well as a high density of excited neutrals. The growth of the plume with repeated bombardment correlates with defect formation as indicated by luminescence intensities.