Growth mechanism of Y123 film by MOD-TFA process

Abstract

In order to clarify the growth mechanism of Y123 film in the metal organic deposition (MOD) process using TFA, transmission electron microscopy (TEM) observation of the quenched samples and measurement of the growth rate under several different conditions were carried out. TEM observation showed that the Y 2Cu 2O 5, BaF 2 and CuO are converted into Y123 by release of HF with supplying H 2O at the reaction interface. The MOD-TFA process using the multi-coating method was applied to form thicker Y123 films on LaAlO 3 substrates, and the growth mechanism for the Y123 crystallization was investigated. In order to evaluate the growth rate, the electrical resistance of the precursor films during the crystallization was measured by the DC four-probe method. It was observed that the thickness of the Y123 linearly increases with increasing annealing time. This result suggests that the growth rate is limited by the HF diffusion in the boundary layer and/or growing interface kinetics. According to the results from the gas flow rate dependence of the growth rate, it was suggested that the growth of Y123 films in this process might be limited by both the diffusion in boundary layer and the interface kinetics. Then, the growth model, which includes the two limiting systems, was developed. This model reveals a basic idea of the mechanism to determine the steady state growth rate.