Surface modification of inorganic solid oxides by excimer laser irradiation

Abstract

TiO2, Nb2O5, Ta2O5, BaTiO3 ceramics were irradiated by a KrF excimer laser in air. A drastic drop of the electrical resistivity was observed on the surfaces. The resistivity of the irradiated surfaces decreased with increasing temperature, which shows that they had changed into a semiconducting phase. This was determined to be n-type by measuring the thermo-electromotive power. The semiconducting property is due to lattice defects which result from ablation of oxygen atoms. When a XeCl excimer laser was used on originally pure oxides. the binary ceramic compounds changed also to semiconductor, but BaTiO3 did not. The energy density threshold of producing a semiconducting phase was correlated with interatomic bond energy of the oxides.TiO2, Nb2O5, Ta2O5, BaTiO3 ceramics were irradiated by a KrF excimer laser in air. A drastic drop of the electrical resistivity was observed on the surfaces. The resistivity of the irradiated surfaces decreased with increasing temperature, which shows that they had changed into a semiconducting phase. This was determined to be n-type by measuring the thermo-electromotive power. The semiconducting property is due to lattice defects which result from ablation of oxygen atoms. When a XeCl excimer laser was used on originally pure oxides. the binary ceramic compounds changed also to semiconductor, but BaTiO3 did not. The energy density threshold of producing a semiconducting phase was correlated with interatomic bond energy of the oxides.