Selective-area metal-organic vapor phase epitaxy for monolithically-integrated semiconductor photonic circuits

1. 利用椭圆偏振光谱对金属-有机气相外延（MOVPE）进行了原位监测，并展示了其对生长表面状态的观测能力。利用观察结果，制备了具有1 ~ 3个分子层的InGaAs/InP量子阱，并用CTR方法对其进行了表征。CTR表征的信号优于以往的任何报道，因此我们证实了它们的界面是真正的单层突然。通过制备特殊的感受器，对InP和GaAs MOVPE中沿前驱体流动方向的生长速率和薄膜质量的纵向分布进行了实验研究，并与新开发的生长模拟器进行了比较。在此基础上，我们明确了高温下表面粗糙度形成的机理，并对避免表面粗糙度产生的生长条件进行了合理的确定。金属-有机气相扩散增强选择性区域外延作为单片光子集成电路中的有源/无源集成技术，我们提出并发展了金属-有机气相扩散增强选择性区域外延（MOVE）。利用这一技术，我们可以实现1.55 μ m的有源区和无源区带隙差在块状材料中（由于成分变化）可达200nm，在量子阱中（由于成分和厚度变化）可达500nm。这些数字远远大于传统的数字。为了能够统一的理解MOVPE中选择性面积的增长，我们开发了一个通用的模拟器。利用能够独立考虑横向蒸汽扩散和横向表面迁移影响的二维模型，可以成功地解释实验结果。结果表明，在常规的选择面积生长中，表面迁移通道占主导地位，而在MOVE中，横向蒸汽扩散通道占主导地位。MOVE是目前世界上唯一能够形成波导阵列的选择性面积生长技术。利用这一特性，我们首次成功地利用选择性面积外延技术制备了1x2 MMI耦合器。此外，利用有源/无源集成能力，我们首次制作了用于光子开关的光放大器门开关电路，并验证了其工作原理。少

1. In-situ monitoring of MOVPE by spectroscopic ellipsometryWe here tried in-situ monitoring of metal-organic vapor phase epitaxy (MOVPE) by spectroscopic ellipsometry, and showed its ability to observe growth surface state. Applying the results of the observation, we made InGaAs/InP quantum wells having 1 to 3 molecular layers, and characterized them using CTR method. The signals from the CTR characterization were found to be superior to any previous reports, thereby we confirmed that their interfaces were truly monolayer abrupt.2. Longitudinal analysis of growth rate and film quality and Its application to growth condition optimizationWe experimentally investigated longitudinal distribution of growth rate and film quality along the direction of precursor flow in InP and GaAs MOVPE by preparing a special susceptor, and compared the results with our newly developed growth simulator. Based on the results, we specified the mechanism of surface roughness formation at high temperatures, an … More d made logical determination of growth conditions for avoiding the surface roughness possible.3. Development of metal-organic vapor-phase-diffusion-enhanced selective-area epitaxyAs an active/passive integration technology in monolithic photonic integrated circuits, we proposed and developed metal-organic vapor-phase-diffusion-enhanced selective-area epitaxy (MOVE). By utilizing this technique, we could achieve band gap difference between active and passive regions at 1.55mum as large as 200nm in bulk material (due to composition variation), and as large as 500nm in quantum wells (due to composition and thickness variation). These numbers are by far larger than conventional ones.4. Simulation of selective-area MOVPEFor the purpose of understanding selective-area growth in MOVPE in a unified manner, we developed a universal simulator. By utilizing a two dimensional model that could take the effects of lateral vapor diffusion and lateral surface migration independently into account, we could explain the experimental results successfully. It was shown that, in the conventional selective-area growth, the surface migration channel was dominant whereas, in the MOVE, the lateral vapor diffusion channel was dominant.5. First fabrication of photonic devices and integrated circuits by MOVEThe MOVE is the only selective-area growth technology in the world which is able to form waveguide arrays. By applying this feature, we succeeded in fabricating 1x2 MMI couplers by selective-area epitaxy for the first time. Furthermore, by utilizing active/passive integration capability, we fabricated an optical amplifier gate switch circuit for photonic switching for the first time, and confirmed its operation. Less