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We investigated the impact of electron-beam lithography writing imperfections on the performance of two-dimensional resonant grating notch filters. This large area photonic device provides an interesting benchmark to assess the acceptable limits of unavoidable fabrication errors. We found that field stitching errors up to 100 nm have no detrimental effect on the filter linewidth, whereas a 2.5 nm electron-beam writing resolution, responsible for digitization disorder, is tolerable only for high-index contrast filter designs. Such an electron-beam writing strategy could also be beneficial for photonic crystal guiding structures or any periodic nanopatterned device with which the optical mode interacts with a large number of periodic elementary units. OCIS codes: 050.0050, 220.0220, 050.5745, 220.3740.

The InAs-based nanowires positioned by electron beam lithography are fabricated and the dependence of the diffusion of In species on temperature, group-III and -V source pressure and group-V source combinations by measuring nanowires growth rate for various nanowire spacing is analyzed. The observations demonstrate that the migration length rises with fall in temperature and rise in group-V/group-III source pressure ratio.

A quantitative evaluation of the intrinsic reliability limits of floating-gate (FG) memories in the decananometer range due to the reduction of collective phenomena and to the dominance of single-electron stochastic behaviors is presented. A model that predicts the intrinsic dispersions of the memory retention time and programming window is proposed, and the experimental results obtained on ultrasound memory devices are used to validate this model.

Fabrication processes for silicon nanowires with triangular cross section are presented. Processes based on high-resolution electron beam lithography and anisotropic etching is developed in silicon on insulator substrates.

Organic thin-film transistors (OTFTs) are fabricated with channel lengths as small as 10nm and an operating voltage of V(sub DD)= -0.3 V using e-beam lithography. Parasitic resistance and contact issues between pentacene and the source/drain contact material resulted in substantial device performance degradation, including a reduction in extrinsically measured transconductance and mobility.

A substantial reduction in the spot size of a 7.2 MeV, 3 kA electron beam illuminating a thin aluminized mylar target has been observed during a 60 ns pulse. We attribute this to the emission of positive ions from the target, under the influence of the high energy flux of the beam, which perforates the target. These ions are then accelerated upstream and focused along the axis by the electron beam, where they partially neutralize the space-charge of the beam and produce a sharp pinch. After the pinch, the beam expands and forms filaments at the end of the pulse. By varying the initial beam transverse size, we have studied the influence of the beam density on the effect. A simulation of the effect with a particle-in-cell code provides a qualitative description and suggests that the ions responsible for the effect are Al(super +) and O(super +). Index Terms: Electron beams, induction machine, particle beam measurement, secondary ion emission.

Two different lithographic techniques have been developed for fabricating magnetic nano-elements on ultra-thin electron-transparent substrates thereby allowing transmission electron microscopy to be used to investigate their properties. Here we describe studies of elements of micropolycrystalline permalloy and cobalt whose thicknesses lie in the range 20-30nm. Bright field images show that a high degree of edge acuity is attained and elements with lateral dimensions [approximately equal to]25nm have been produced. Lorentz microscopy has provided unique insight into the detailed magnetisation reversal mechanisms in acicular elements with widths in the range 100-300nm. In cobalt elements a single domain occupies most of the volume with complex domain structures existing very close to the ends; switching fields increase markedly with decreasing element width but are substantially independent of element length. The reversal mechanism is found to involve the propagation of a small 'reversing' domain structure along the element length. In permalloy, extensive domain structures are observed in all but the narrowest elements in the remanent state. The response to applied fields is described.

A new-channel-waveguide-fabrication process for use with polyimide is described. The new technique uses an electron-beam-induced effect to alter the refractive index of the polyimides directly. Channel waveguides with an 8-[[micro]meter]-wide, 8-[[micro]meter]-deep core have been fabricated on a polyimide film by the use of electron-beam irradiation. Only one kind of polyimide (6FDA/TFDB) was used in this waveguide. The difference in refractive index between the core and the cladding was approximately 0.30% for both TE-and TM-polarized incident light when the dose was 1500 [micro]C/[cm.sup.2], which was sufficient to produce waveguides. The optical properties of the waveguide are also demonstrated.

Discrete track recording technology offers a potential advantage in reducing adjacent track erasure/interference. As nano-imprinting technology advances, fabrication of such media has been demonstrated. In recent years, discrete track recording has generally been viewed as one of the next promising technologies for areal density advancement. In this study, we evaluated the recording performance of PMR media with patterned tracks. To accurately assess the advantage of discrete track performance and compare with current continuous media, both recording performances were measured on one single track. The head flying height is monitored on the patterned and continuous media regions. At 100-nm data track width, patterned tracks show noticeably better signal-to-noise ratio and significantly lower adjacent track erasure compared with continuous media at the same track width. Such measured performance advantages are critical to increase track density beyond 300-400 ktpi. Index Terms--Electron beam lithography, patterned media, perpendicular magnetic recording (PMR).

The magnetic properties of submicron circular epitaxial Co dot arrays fabricated by electron beam lithography are studied as a function of thickness using high resolution magnetic force microscopy. As a function of thickness, in-plane single domain, vortex, or perpendicular multidomain phases are identified.

A new processes for fabricating NiO exchange bias layers has been developed. The process involves the direct ion beam sputtering (IBS) of a NiO target. The process is simpler than other deposition techniques for producing NiO buffer layers, and facilitates the deposition of an entire spin-valve layered structure using IBS without breaking vacuum. The layer thickness and temperature dependence of the exchange field for NiO/NiFe films produced using IBS are presented and are similar to those reported for similar films deposited using reactive magnetron sputtering. The magnetic properties of highly textured exchange couples deposited on single crystal substrates are compared to those of simultaneously deposited polycrystalline films, and both show comparable exchange fields. These results are compared to current theories describing the exchange coupling at the NiO/NiFe interface.

We describe a new method for producing ultrafine magnetic particles that employs pulsed-laser particle ablation. Pulsed-laser radiation with wavelength of 248 nm was used to ablate 1 to 10 [[micro]meter] diameter permalloy microparticles under normal atmospheric conditions. The ejected nano-particles were collected on silicon substrates for further analysis. Scanning electron micrographs of the samples were analyzed by computer aided image processing to determine the effect of laser fluence on the particle size distribution. Results showed that mean particle diameters were in the range from 60 to 90 nm, and that the particle size distributions were closely log-normal.

We have fabricated arrays of Co dots having diameters of 100 nm and 70 nm using interference lithography. The density of these arrays is 7.2x[10.sup.9]/[in.sup.2]. Magnetic force microscopy measurements indicate that the Co dots are single-domain with moments that can be controlled to point either in-plane or out-of-plane. Interference lithography is a process that is easily scaled to large areas and is potentially capable of high throughput. Large, uniform arrays of single-domain structures are potentially useful for high-density, low-noise data storage.

We report the fabrication methods of vertical type spin-valve(SV) sensors with a quarter micron trackwidth using electron beam lithography and ion beam etching. A double-layer resist system which simultaneously solves the problems of resist residuals and the redepositions have been investigated. This method was successfully applied to fabricate IrMn-SV sensors with a 250 nm trackwidth. Transfer curve measurements showed degradation of GMR ratio from 11 % to 7% after fabrication. However, this degradation was not thought inherent to this process. Index Terms--electron beam lithography, GMR, spin-valve, nanofabrication

A novel method for patterning individual metallic nanoclusters with tunable and monodisperse sizes down to 2 nm scale into desired arrays is presented, using an electron-beam lithography technique that has a resolution of ~20 nm. Besides catalytic nanosynthesis, this method might prove to be powerful in various scientific and technological applications, ranging from catalysis, surface science, single-molecule spectroscopy, and data storage.