Defect Engineering and Characterization in Oxide Surfaces using Electron Beam Irradiation

Abstract

ABSTRACTElectron beam irradiation at energies between 0.5 and 4 keV has been found to produce defects in oxide materials including SiO2, Al2O3 and ZrO2. These defects trap excess charge in the materials and affect their electronic and optical properties. Measurements of the thermally stimulated exoelectron emission following irradiation provides information on relative defect concentrations, defect creation mechanisms, electron trap binding energies, electron emission mechanisms and annealing properties of these materials. Electron emission during sample heating occurs via a variety of mechanisms including the thermionic emission of excess charge from defects at temperatures characteristic of each trap binding energy. By measuring relative trap concentrations as a function of beam parameters, we have identified electron beam energy thresholds for the creation of some types of defects which correlate with core level electronic transitions. Also, electron emission which occurs during defect annealing or diffusion to a surface shows the conditions for the elimination of defects. The ability to control and characterize defect formation and annihilation provides the possibility of engineering specific surface defect conditions. In addition, defect creation by electronic processes is very selective as compared with momentum transfer in ion beam damage of surfaces.