Yu-Cheng Chang

Microwave rapid heating for the synthesis of gold nanorods

A microwave heating system with a sealed reaction chamber and a precise temperature-controlled module was employed to assess the synthesis of tetradecylammonium bromide (TOAB) cation surfactant-stabilized gold nanorods. Scanning electron microscopy (SEM) was employed to characterize the size and the shape of particles. It was found that both TOAB concentrations and reaction temperature programs played an important role in the formation of gold nanorods. By using higher TOAB concentration and faster rising reaction temperature, gold nanorods with higher aspect ratio could be produced. This finding demonstrated the combination of TOAB surfactant and microwave system to be a useful approach for the preparation of gold nanorods.

Microwave Heating for the Preparation of Nanometer Gold Particles

In this paper we report a feasible method to synthesize gold nanoparticles with uniform size by microwave heating. In this work, a closed chamber of a microwave system with precise temperature control function was employed to synthesize the gold nanoparticles. Our data demonstrates that the temperature plays an important role in the synthesis of gold nanoparticles. With higher synthesis temperature, longer heating time duration and rapid gradient of temperature increase, the smaller diameter and the narrow size distribution of the gold nanoparticles were obtained. The concentrations of citrate represent the reductant in the synthesis reaction, which also influence the morphology of gold nanoparticles. The data demonstrates that gold nanoparticles with highly reproducible sizes could be synthesized by microwave heating.

Rapid fabrication of high quality self-assembled nanometer gold particles by spin coating method

This paper reports the fabrication of self-assembled gold nanoparticles attached to 3-aminopropyltrimethoxysilane (APTMS) modified fused silica substrates by the spin coating method. With the spin coating method, the gold nanoparticles can be fabricated on fused silica substrates with highly packing density in a short processing time. Our results clearly demonstrate that the spin coating method takes advantages of shorter fabrication time, higher uniformity, and better reproducibility when compared with the traditional immersion method.

The structure identification of epitaxial Ru2Si3 on (111) Si

Abstract Epitaxial Ru 2 Si 3 has been successfully grown on (111) Si for the first time by using the new method of chemical electroless plating of Ru thin film on silicon with subsequent annealing schemes. The crystal structure of Ru 2 Si 3 reported in the literature, which was identified by X-ray diffraction, was ambiguous to be tetragonal or orthorhombic. The study of stereomicroscopy and Kikuchi lines of the Ru 2 Si 3 by scanning transmission electron microscopy shows that the structure of Ru 2 Si 3 is orthorhombic with four-fold like symmetry rather than tetragonal.

InP/InGaAlAs distributed Bragg reflectors grown by low-pressure metal organic chemical vapor deposition

Abstract Long-wavelength vertical cavity surface emitting lasers (VCSELs) are considered the best candidate for the future low-cost reliable light sources in fiber communications. However, the absence of high refractive index contrast in InP-lattice-matched materials impeded the development of 1.3–1.5xa0μm VCSELs. Although wafer fusions provided the alternative approaches to integrate the InP-based gain materials with the GaAs/AlAs materials for their inherent high refractive index contrast, the monolithic InP-based lattice-matched distributed Bragg reflectors (DBRs) are still highly attractive and desirable. In this report, we demonstrate InP/InGaAlAs DBRs with larger refractive index contrast than InP/InGaAsP and InAlAs/InGaAlAs DBRs. The switching between InP and InGaAlAs layers and growth rate control have been done by careful growth interruption technique and accurate in situ optical monitoring in low-pressure metal organic chemical vapor deposition. A 35 pairs 1.55xa0μm centered InP/InGaAlAs DBRs has the stopband of more than 100xa0nm and the highest reflectivity of more than 99%. A VCSEL structure incorporating 35 pairs InP/InGaAlAs DBR as the bottom mirror combined with a 2 λ thick periodic gain cavity and 10 pairs SiO 2 /TiO 2 top dielectric mirrors was fabricated. The VCSELs lased at 1.56xa0μm by optical pumping at room temperature with the threshold pumping power of 30xa0mW.

Synthesis of silver nanorods by microwave irradiation

Microwave-assisted heating provides a rapid method for the preparation of silver nanorods due to its fast-heating characteristic. With these preliminary studies, we demonstrate the potential of the microwave rapid heating process for the synthesis of silver nanorods and nanowires.