Fabrication of novel monolithic optical devices composed of blue laser diodes and ferroelectric optical waveguides

为了开发由蓝色激光二极管和铁电光波导组成的新型单片光学器件，将铁电锆钛酸铅（PZT）薄膜沉积在氮化镓（GaN）上。采用脉冲激光烧蚀的方法，首次在金属有机气相外延法在（001）GaAs上制备的立方GaN上沉积了PZT薄膜。PZT薄膜在有MgO缓冲层的GaN上优先取向[100]，而PZT薄膜在没有MgO缓冲层的情况下是随机取向的。这种差异的原因被认为是MgO缓冲层在PZT和GaN之间起到了扩散屏障的作用。研究了结晶度与抗氧化性能之间的关系。结果表明，结晶度较低的氮化镓具有较高的电阻率。在500℃左右的氧气环境中，结晶度下降，表面粗糙度降低。

In order to develop novel monolithic optical devices composed of blue laser diodes and ferroelectric optical waveguides, ferroelectric lead zirconate titanate (PZT) films were deposited on gallium nitride (GaN). PZT films were deposited by pulsed laser ablation on cubic GaN prepared on (001) GaAs by metalorganic vapor phase epitaxy for the first time. PZT films were preferentially [100] oriented on GaN with MgO buffer layers although PZT films were randomly oriented without MgO buffer layer. The origin for the difference is thought that MgO buffer layer acts as a diffusion barrier between PZT and GaN.Relationship between the crystallinity and the resistance against oxidation was also studied. It was found that GaN with lower crystallinity shows higher resistivity. It was also revealed that the crystallinity degrades and the surface roughness decreases both with an exposure to oxygen atmosphere around 500 ℃.