Fabrication of the oxide single crystal film by Tri-phase Epitaxy

三相外延（TPE）是一种新的气相外延单晶氧化物薄膜的方法，主要是在体单晶工艺中发展起来的。也就是说，膜在足够高的温度下通过焊剂的液体层生长，以在生长的膜和焊剂之间获得热力学稳态条件。在本项目的第一年（H14），我们尝试将热塑性弹性体应用于钙掺杂Nd_（123）和Bi_4Ti_3O_（BIT）单晶薄膜的制备。<7-d><12>同时，我们还开发了一种新的三元组分扩散组合系统，以加快实验工作的速度。在第二年（H15），通过三元组分扩散技术的高通量筛选，成功地发现了一种新的BIT单晶薄膜的Bi-Cu-O杂质通量。在生长过程中添加CuO_x助熔剂可以抑制BiO_x助熔剂的蒸发。结果，获得了BIT膜的单晶质量，这通过没有从衬底的台阶和/或膜中的晶格失配继承的滑动位错和缺陷来证明。另外，我们还发现PLD生长的BIT薄膜表面覆盖有BiO_x，经过高温退火后，BIT薄膜变成了单晶。这一初步结果表明，通过将TPE应用于固相反应，“固相助熔剂外延”的新的可能性。

Tri-phase epitaxy (TPE) is a new approach in vapor phase epitaxy for a single crystal oxide film based on a flux method primarily developed in a bulk single crystal process. That is, the film is grown through a liquid layer of the flux at a high temperature enough to attain a thermodynamic steady-state condition between the growing film and the flux. We have verified the capability of the TPE by fabricating a single crystal film of NdBa_2Cu_3O_<7-d> (Nd123).In the first year for this project (H14), we attempted to apply the TPE to the fabrications of Ca doped Nd123 and ferroelectric Bi_4Ti_3O_<12> (BIT) single crystal films. In parallel, we also developed a new combinatorial system for a ternary composition spread to speed up the experimental work.In the next year (H15), a new impurity flux of Bi-Cu-O for the BIT single crystal film was successfully found from a high-throughput screening by the ternary composition spread technique. The additional CuO_x flux could suppress an evaporation of the BiO_x flux during the growth. As a result, the single crystal quality of the BIT film was achieved, which was evidenced by no sliding dislocations and defects inherited from steps of a substrate and/or the lattice mismatching in the film. In addition, we found that the PLD grown BIT film with its surface capped with the BiO_x became single crystalline after annealing at high temperature. This preliminary result suggests a new possibility of "solid phase flux epitaxy" by applying the TPE to the solid phase reaction.