Constrained Growth of the PMMA Photonic Crystals

The constrained growth was observed during the formation process of the photonic crystals from the monodispersed PMMA colloidal microsphere and a controllable vertical deposition (CVD) technology was developed to prepare the photonic crystal based on these growth behaviors and the PMMA colloid particles with size of 345nm were assembled into the 3-D arrays. The transmittance spectrum of the typical sample exhibited an enlarged transmission mode. Their SEM observation revealed that the bulk structure of the crystalline array had a high periodical and long range order, the perfect order zone was above 20μm and the surface of the crystal was complete flat and had only two vacancies in the 35 μm order zone. The growth interface analysis indicated that the colloidal spheres sedimented subsequently and the drying front between the suspension and crystal moved at a constant velocity with time. The crystals developed by the continuous growth mechanism and the growing crystals had rough interface during the process of controllable vertical deposition.