| Research Abstract |
1. In-situ monitoring of MOVPE by spectroscopic ellipsometry
We 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 optimization
We 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
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d made logical determination of growth conditions for avoiding the surface roughness possible.
3. Development of metal-organic vapor-phase-diffusion-enhanced selective-area epitaxy
As 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 MOVPE
For 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 MOVE
The 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
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