[en] Time-varying axial magnetic field of approximately 10-15 G is added to an inductively coupled plasma. High aspect ratio deep-sub-micron contact holes in borophosphosilicate glass have been etched by C₄F₈/Ar plasma. In order to correlate etched profile with etching conditions, deposition of polymeric precursors in the etching process is monitored. By means of the appearance mass spectroscopy, the distributions of CF_x⁺ ions and CF_x radicals are measured as a function of the frequency of axial magnetic field. The axial magnetic field is found to influence the densities of fluorocarbon ions (CF_x⁺; x=1-3), F and CF_x radicals. X-ray photoelectron spectroscopy shows that fluorocarbon polymer on oxide surface strongly varies with the frequency of axial magnetic field. 0.2 μm diameter contact holes with aspect ratio of 10 are successfully fabricated in this system

[en] We report on the design of nanoring resonators made of metal-insulator-metal (MIM) nanostrip waveguides. The characteristics of the lightwave propagation through the silver-based MIM plasmonic waveguides with an air superstrate are examined. The effective refractive indices, the propagation losses, the bending losses, and the beat lengths are analyzed by using 2D and 3D finite element methods (FEMs). For the optimization of the nanoring resonators, we examined the resonant mode power and the Q factor with respect to the width of the MIM nanostrip and the separation between the ring resonator and the straight waveguide. We obtained an optimized nanoring resonator that had submicron diameters (R = 399 nm) and 3^rd-order resonances at a 1550-nm wavelength. These nanoring resonators will play an important role as the basic building blocks for the realization of nanoscale photonic integrated circuits.

[en] As the optical confinement factor (Γ) of a laser diode is maximized at the thickness of SCHΓ_max (Separate Confinement Heterostructure for maximum Γ), the linewidth enhancement factor (α) is also expected to be improved for a thickness near SCHΓ_max . Although the improvement in α with decreasing SCH thickness for thicker SCH (> SCHΓ_max) is well-known, to the best of our knowledge, it has not been measured for thin SCH (< SCHΓ_max). We report the measured α curves of three distributed feedback laser diodes with different SCH thicknesses of 500, 750, and 1000 A, which are all smaller than SCHΓ_max (∼1500 A for the 1.24-μm p-InGaAsP layer given here). Additionally, the optical field profiles for various SCH thickness were calculated to estimate the corresponding optical confinement factors for comparison with the variation of the measured α. It is shown that α is improved as the SCH thickness increases for thin SCH (< SCHΓ_max)

[en] In order to manufacture a carbon nanotube (CNT) tip in which the attachment angle and position of CNT were precisely adjusted, a nanomanipulator was installed inside a scanning electron microscope (SEM). A CNT tip, atomic force microscopy (AFM) probe to which a nanotube is attached, is known to be the most appropriate probe for measuring the shape of high aspect ratio. The developed nanomanipulator has two sets of modules with the degree of freedom of three-directional rectilinear motion and one-directional rotational motion at an accuracy of tens of nanometers, so it enables the manufacturing of more accurate CNT tips. The present study developed a CNT tip with the error of attachment angle less then 10 deg. through three-dimensional operation of a multiwalled carbon nanotube and an AFM probe inside a SEM

[en] We report on the possibility of applying atomic force microscope (AFM) lithography to draw micro/nano-structures on the surface of a polycarbonate (PC) substrate. We also fabricated a grating structure on the PC surface using the scratch method. An AFM silicon tip coated with a diamond layer was utilized as a cutting tool to scratch the surface of the sample. In order to obtain pattern depth deeper than the control method of interaction force, we used a scanner movement method which the sample scanner moves along the Z-axis. A grating of 100 μm x 150 μm was fabricated by the step and repeat method wherein the sample stage is moved in the direction of the XY-axis. The period and the depth of the grating are 500 and 50 nm, respectively. Light of 632.8 nm wavelength was diffracted on the surface of the PC substrate.

[en] When viewed at frequencies below about 8 THz (250 cm^-1; 30 meV) the ab-plane optical conductivity of the cuprate superconductors (in their normal state) is well described by a Drude model. Examples include optimally-doped YBa₂Cu₃O_7-δ and Bi₂Sr₂CaCu₂O₈; even the underdoped phases have a Drude character to their optical conductivity. A residual Drude-like normal fluid is seen in the superconducting state in most cases; the scattering rate of this quasiparticle contribution collapses at T_c. (Abstract Copyright [2006], Wiley Periodicals, Inc.)