A new cooling plus heating mode of liquid phase epitaxy and its application for oriented film growth

Abstract

Using liquid phase epitaxy (LPE), we developed a new approach to growing a-axis oriented YBa₂Cu₃O_7−δ films (a-films) in air, which have been hard to gain in the prior art since an extremely low supersaturation (σ) is required for their formation. Instead of the conventional step-cooling from a high temperature (T_h) above the peritectic temperature (T_p) directly to the growth temperature (T_g), a novel cooling plus heating mode (from T_h cooling down to below T_g and then heating back to T_g) was adopted for the film growth. We found that slow cooling combined with fast heating was effective to achieve an extraordinarily low σ for preparing a-films, which are potentially appropriate for Josephson junction devices. Most importantly, the correlation between the cooling mode and the driving force was reviewed, which provided universal guidance for finely tuning supersaturation of the solution.