THE PREPARATION AND CHARACTERIZATION OF ALPO4 THIN-FILMS VIA LASER-ABLATION OF ALPO4-H-4

An excimer laser (KrF, 248 nm) was used to deposit well-dispersed thin films of aluminum phosphate onto a titanium nitride substrate from an AlPO4-H-4 target. It was found that laser ablation of AlPO4-H-4 results in AlPO4 cristobalite or aluminum orthophosphate as well as AlPO4 tridymite and amorphous materials depending upon the conditions. The effects of laser power, substrate distance, atmosphere, and temperature on thin-film formation were studied. Low substrate temperatures and pulse energies between 50 mJ and 100 mJ resulted in growth of AlPO4 cristobalite or aluminum orthophosphate. Low laser-power density and high substrate temperatures produced AlPO4 tridymite on the substrate TiN surface. These first examples of laser-ablated AlPO4 films were characterized by X-ray diffraction, X-ray fluorescence, infrared spectroscopy (FTIR) and scanning electron microscopy.