OZONE JET GENERATOR AS AN OXIDIZING REAGENT SOURCE FOR PREPARATION OF SUPERCONDUCTING OXIDE THIN-FILM

An ozone jet generator to supply precisely controlled ozone flux to a specimen was constructed with the particular aim of its application for the preparation of superconducting oxide thin films by an MBE (molecular beam epitaxy) method. The ozone jet is supplied to the thin film growth chamber by evaporating the liquid (or solid) ozone accumulated in the ozone vessel of the generator. The necessary condensed ozone is produced from the ozone-oxygen mixture gas generated by a commercial ozonizer. The ozone flux can be changed by adjusting the temperature of the ozone vessel (i.e., the temperature of liquid ozone). Precise pressure and temperature control of the ozone vessel in liquefying ozone makes it possible to minimize dissolution of diatomic oxygen in the liquid ozone. As a result, the ozone jet generated from the liquid ozone possesses high purity. The precise temperature control also enables a very stable supply of the ozone jet, with a stability of less than 2.5% over 1.5 h. For the experimental condition of liquefying ozone at 95 K and 800 Pa, and evaporating at 85 K, an ozone jet with an ozone flux of 1 x 10(16) molecules/s and an ozone concentration of higher than 70% was obtained in the test vacuum chamber installed with this ozone jet generator. It was also confirmed by XPS spectra of Cu after oxide film formation that the ozone jet possesses a very high reactivity.