Methods for the control of molecular deposition and orientation are critical for the development of organic electronic devices. Here, we show the fabrication of ribbons of the optical material polydiacetylene (PDA) using a controlled evaporative self-assembly method. The ability to form these ribbons is highly dependent on both the side groups on the PDA as well as the solvent used in the preparation. Arrays of ribbons of one type of PDA, poly[1,6-di(N-carbazolyl)-2,4-hexadiyne], with widths on the order of 1–2 µm and lengths of 100s of micrometers, could be successfully obtained with good orientation.

The refractive index change of polariton propagation in a GaAs quantum-well waveguide was measured as a function of the electric field. Its temperature dependence was also measured. The experimental results showed that the refractive index change of the polariton propagation was at least three times as large as that of the conventional light propagation. This effect remains up to 40 K, and coincides with the temperature dependence of the rate of polariton scattering by phonons. We also Fabricated directional-coupler-type switching devices to apply this large refractive index change, and were able to demonstrate the operation in a single quantum-well waveguide. Our results indicate that extremely small and low driving voltage switching devices may be feasible.

Accelerated aging tests have been conducted to evaluate the long-term durability of cementitious material against aggressive ions. In tests, cementitious specimens were immersed in the solutions containing concentrated aggressive ions at high temperature and it promoted diffusion of the ions in the specimen. This method would be suitable for the evaluation on the aging as the alteration of the specimen would be expected to resemble the natural behavior. This paper presents a classification of alteration mechanism in the immersion tests using MgCl2 and Na2SO4 solution. This classification was done by relating the changes of compressive strength to microscopic and mineralogical changes.

Selective epitaxial growth of III-V compounds based on GaAs has been achieved using Ar+ ion laser assisted chemical vapor deposition (LCVD) on GaAs substrates. The growth rate, at carefully selected growth conditions, can be controlled to a few Å/s at bias temperatures as low as 250°C by conventional LCVD multi-scan technique. Typical Gaussian thickness profiles are achieved by this growth technique. On the other hand, flat top thickness profiles are achieved with direct writing of GaAs mono-layers by laser assisted atomic layer epitaxy (LALE). X-ray topography is demonstrated as a powerful tool for characterizing the grown films and photoluminescence shows that the quality of the grown films are comparable with those grown by conventional MOCVD or ALE.

InSb1−x Bix (0.01 < × < 0.14) and InAsSbBi quaternary alloys are potentially attractive materials for the development of semiconductor infrared detectors covering the 8–14 μm range [1,2,3].

We report for the first time, MOCVD growth of InSo1−x Bix (0.01 < × < 0.14) and InAs1−x−y Sbx Biy with 0.5 < × < 0.7 and 0.01 < y < 0.04 on both GaAs and InSb substrates using AsH3, TMSb, TEI and TMBi. Electrical measurements of the undoped InSo0.99 Bi0.01 shows a background carrier concentration of approximately 1016/cm3 and a room temperature mobility of 20,215 cm2/V.sec. To-date, these are the best reported electrical measurements for this ternary alloy.

The formation of a secondary Bi phase and single crystal growth of metallic bismuth-antimony at the surface of InSo1−x Bix which results in deterioration of morphology with increasing values of x is also investigated. A wide range of analytic techniques, including SEM, EDX, electron microprobe and AES have been employed in our surface analysis.