Efficient fabrication of wafer scale thin film of individualized single-walled carbon nanotubes by dual-nozzle spin casting.

In this paper, a dual-nozzle spin casting method was proposed to form a thin film of individualized single-walled carbon nanotubes (SWNTs) at the wafer scale. Each nozzle simultaneously ejected the SWNT solution and methanol, respectively. During the ejection process, two solutions were mixed at the contacting end of the nozzles and then dropped onto the substrate. Functionalization of the wafer substrate with the amine group improved the uniformity of the SWNT thin film as well as the adhesion between the individualized SWNTs and the substrate. The best condition of the spin casting involved the substrate functionalization using 3-aminopropyltriethosilane aqueous solution with a concentration of approximately 10 mM and a deposition velocity of approximately 5000 rpm. The root-mean-square roughness of the fabricated SWNT layer over the wafer substrate was found to be 1.4-1.8 nm, which indicated that the resultant thin film was one or two layers of SWNTs. The wafer scale SWNT thin film formed by dual-nozzle spin casting can be further used for the mass production and high integration of the SWNT nanoelectronic devices.

Separation algorithm for a 2D refractive index distribution and thickness profile of a phase object by laser diode-based multiwavelength interferometry.

A separation algorithm that uses three wavelengths for the simultaneous measurement of the two-dimensional refractive index distribution and thickness profile of transparent samples is proposed. The optical system is based on a Mach-Zehnder interferometer with laser diode-based multiwavelength sources. A liquid crystal retarder is used to obtain interference images at four states with phases, and the optical phase of the object is then calculated with a four-bucket algorithm. A glass rod and several samples, including a slide glass, a glass wafer, and a cover glass are used to obtain experimental results at wavelengths of 635, 660, and 675 nm. The refractive indices of the sample are distributed with an accuracy of less than 0.0003 and the thickness profile is calculated on the basis of the measured refractive index. This result demonstrates that the proposed algorithm can be used to separate the refractive index distribution and thickness profile of samples in two dimensions.

Preferential elimination of metallic single-walled carbon nanotubes using microwave irradiation.

This study presents a simple, easy and rapid technique for the preferential destruction of metallic single-walled carbon nanotubes (m-SWNTs) using microwave irradiation. The proportion of m-SWNTs in a randomly networked film that were made of pristine SWNTs was gradually reduced with microwave irradiation of 1000 W at 2.45 GHz ranging from 0 to 20 min. Additionally it was observed that the m-SWNTs with a higher chiral angle were destroyed first. The Raman spectra and drain current-gate voltage characteristics curve show that this method facilitated the selective removal of m-SWNTs.

Angle-resolved annular data acquisition method for microellipsometry.

An ellipsometric data acquisition method is introduced to measure the optical properties of sample. It is based on a microellipsometer hardware layout integrated a high numerical aperture objective lens, which is aligned in the normal direction of sample surface. This technique enables to achieve ellipsometric data at multiple incident angle with a sub-mum probe beam size, moreover real-time measurement is possible due to no moving parts. The experimental results of different SiO(2) thin film are demonstrated, also calibration technique is described.