Tomoaki Hayano

Quantum wire and dot formation by chemical vapor deposition and molecular layer deposition of one‐dimensional conjugated polymer

Using the reaction between two types of molecules, I [terephthalaldehyde (TPA)] and II [p‐phenylenediamine (PPDA), 4,4’‐diaminodiphenyl ether (DDE), 4,4’‐diaminodiphenyl sulfide (DDS), or 1,4‐diaminodiphenylmethane (DDM)], we fabricate quantum wires and quantum dots by chemical vapor deposition. In the TPA/PPDA film, an exciton absorption peak occurs near 500 nm, indicating that long conjugated chains (quantum wire) are formed. In TPA/DDE, TPA/DDS, and TPA/DDM films, which have quantum dots consisting of three benzene rings separated by barriers of ‐O, ‐S‐, and ‐CH2‐ bonds, blue shifts of the absorption band occur due to an electron confinement. We also demonstrate molecular layer deposition of the TPA/PPDA film.

Polyazomethine conjugated polymer film with second order nonlinear optical properties fabricated by electric‐field‐assisted chemical vapor deposition

We fabricated polyazomethine head‐to‐tail conjugated polymer films with second order nonlinear optical (NLO) properties using a dry‐processing technique, electric‐field‐assisted chemical vapor deposition (E‐CVD). Molecular orbital calculations show that the polyazomethine conjugated polymer chain, to which methoxy groups are attached as donors, has second order NLO susceptibility, β, 3–5 times larger than that of paranitroaniline. During film deposition the monomers were ordered by an electric field applied between slit‐type electrodes, and simultaneously polymerized. A channel waveguide for the TE mode of a He‐Ne laser beam was formed in a polymer film between the electrode gap. An electro‐optic (EO) effect in the polymer film was observed using a Mach–Zehnder interferometer. This indicates that head‐to‐tail conjugated polymers would be promising for second order NLO materials.

Selectively Aligned Polymer Film Growth on Obliquely Evaporated SiO2 Pattern by Chemical Vapor Deposition

Polyazomethin films were grown by chemical vapor deposition using terephthalaldehyde and p-phenylenediamine gases on SiO2 film patterned in a 10-µm-wide stripe. When the SiO2 film was obliquely evaporated on a quartz substrate by tilting the substrate along the y-axis, while polymer chain alignment was random on the quartz, the chain on the SiO2 film aligned along the y-axis, which induced birefringence and dichroism selectively on the stripe pattern. When the SiO2 stripe was formed on a SiO2 film deposited by tilting the substrate along the x-axis, the chain direction in the stripe region was at right angles to that in the surrounding region.