| Co-Investigator(Kenkyū-buntansha) |
SATO Taketomo Hokkaido University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (50343009)
HASHIZUME Tamotsu Hokkaido University, Research Center for Integrated Quantum Electronics, Associate Professor, 量子集積エレクトロニクス研究センター, 助教授 (80149898)
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| Research Abstract |
We have developed a technique to form two-dimensional periodic array of hexagonal pillars and air-hole structures for the application of two-dimensional crystals (2DPCs) by selective area metalorganic vapor phase epitaxial (SA-MOVPE) growth. Firstly, SA-MOVPE of GaAs and AlGaAs was carried out on (111)B GaAs substrates partially covered with SiO_2 masks. Array of circular or hexagonal openings of the mask pattern was arranged to realize triangular lattice with periodicity of about 0.5μm. By optimizing the growth conditions, uniform array of hexagonal pillar structures consisting of vertical {110} facets was successfully grown on the masked substrates, which can be used as 2DPC. Similar array of hexagonal InGaAs pillars was also grown on (111)B InP masked substrates, and was found to exhibit high optical qualify suitable for 2DPCs using InP-based materials. In addition, by growing a masked substrate with hexagonal SiO_2 masks arranged to form triangular lattice, we succeeded in the growth of GaAs 2DPC structures with hexagonal air-hole arrays when the growth conditions were optimized to suppress lateral overgrowth. Furthermore, by growing air-hole type 2DPCs on AlGaAs (111)B surfaces and selective undercut etching of AlGaAs, 2DPC slab was also successfully fabricated. Finally, Photonic bands of 2DPCs consisting of hexagonal air-hole arrays or hexagonal dielectric rods were also calculated by using plane-wave expansion method, and they were compared with those consisting of conventional circular air-holes or circular rods. Although the overall features of the photonic bands quite looked alike, the discrepancy originating from the shape of air-holes and rods were found. Especially in hexagonal air-hole arrays in orthogonal-type triangular lattice, the enhancement of overlap between TM and TE gap demonstrated, which is effective to realize 2D full photonic bandgap.
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