Ultrathin galvanic cells, which can comply with a variety of form factors and electronic system packages, are of technological importance, as they show promise for flexible electronic systems. Here we describe a high energy density flexible galvanic cell, which is non-toxic and environmentally friendly. It operates with a zinc anode and hydrated ruthenium(IV) oxide cathode, where RuO2·nH2O nanoparticles are utilized in amounts that are not cost-prohibitive. As the battery utilizes aqueous electrolytes, it is safe in operation, which enables its use in a number of settings and surroundings. It can be optimized for volume manufacture at low cost. Given that they function at much lower cell voltage than Li-ion batteries do, Zn–RuO2·nH2O cells can be recharged remotely, at a conveniently low voltage, by harvesting, for example, radio-frequency (RF) energy or microwaves. As an additional asset, Zn–RuO2·nH2O electrodes enable battery-supercapacitor hybrid power sources. At present, this cell demonstrates a specific charge capacity of 84.4 mAh per cm2 of projected electrode area, which is, so far, the largest value reported for thin film cells. Also, its cycle life of up to 400 charge–discharge cycles is very promising for use as a secondary battery.

Ultracapacitors represent an essential storage element in a variety of hybrid energy sources, ranging from automobile power systems to low-power motes in a distributed sensor network. Hydrated ruthenium (IV) oxide has demonstrated superior performance in terms of energy storage density (over 25 W h kg(-1)) as compared to other material systems. The cost of the oxide has been, however, a major impediment to the widespread use of this technology. In this article, the authors report on the fabrication of ruthenium (IV) oxide based ultracapacitor/galvanic cell hybrids made with a coating system capable of providing continuous, densely packed (but porous) layers of the nanoparticles with the thickness of one single nanoparticle. (C) 2011 American Vacuum Society. [DOI: 10.1116/1.3524906]

An approach to fabricate a set of simultaneously operating dual-UV-wavelength detectors is described. The fabrication flow relies on the confined-epitaxy growth method. The confined epitaxial AlxGa1-xN-layer stacking approach is used to establish simultaneous multiple UV-wavelength detection. The chosen stoichiometries of specific epitaxial layers set the wavelength sensitivity at approximately 355 nm for pixel A and 320 nm for pixel B. Spectral responsivity plots of the detectors clearly show the dual-UV-color sensitivity of the pair. The detectors have signal-to-noise ratios of 15 and 17 and spectral responsivity values of 0.12 AAV and 0.05 AAV for pixel A and pixel B, respectively.

This article presents the first experimental evidence that plasmonic excitation in metal films perforated with regular arrays of subwavelength apertures can produce high resolution far-field radiation patterns of sufficient intensity to expose photoresist when propagated through the optical system of a conventional stepper. The pattern fill factor (i.e., the total clear aperture area divided by the total mask area) is more than an order of magnitude smaller than the ratio of the mask clear area divided by the total mask area of a conventional mask. This could lead to a significant increase in mask making throughput. Contact window arrays were exposed with critical dimensions down to 260 nm using 248 nm incident radiation. While the exposure times are longer (somewhat less than three times more energy is required on the mask), the image pattern appears to be a cooperative effect of scattering from multiple apertures. If the array is defective, meaning that it contains a small number of unopened apertures, the pattern still prints as a coherent, cleared feature. (C) 2007 American Vacuum Society.

This article presents the first experimental evidence that plasmonic excitation in metal films perforated with regular arrays of subwavelength apertures can produce high resolution far-field radiation patterns of sufficient intensity to expose photoresist when propagated through the optical system of a conventional stepper. The pattern fill factor i.e., the total clear aperture area divided by the total mask area is more than an order of magnitude smaller than the ratio of the mask clear area divided by the total mask area of a conventional mask. This could lead to a significant increase in mask making throughput. Contact window arrays were exposed with critical dimensions down to 260 nm using 248 nm incident radiation. While the exposure times are longer somewhat less than three times more energy is required on the mask , the image pattern appears to be a cooperative effect of scattering from multiple apertures. If the array is defective, meaning that it contains a small number of unopened apertures, the pattern still prints as a coherent, cleared feature. © 2007 American Vacuum Society. DOI: 10.1116/1.2812524

We report enhanced transmission of 250 nm radiation by sub-wavelength square aperture arrays on silver and demonstrate its use in optical lithography with far- reduced number of addressed pixels to produce very good edge acuity.

An approach to reduce vertical threading dislocations in the active regions of III-nitride devices is described. The approach involves confined homo- or heteroepitaxy of GaN materials using sputtered oxide masks to delineate growth regions and conventional metal-organic chemical vapor deposition. The resulting confined epitaxial material is terminated with equilibrium crystal facets, which form hexagonal mesas, and contains a reduced dislocation density and reduced strain compared to the underlying template layer for homoepitaxial growth. Characterization of pn junction diodes grown with this approach reveals significantly reduced leakage currents in as-grown, unpassivated structures (as low as 1×10−7Acm−2).

Initial studies on the fabrication of a new double-layer capacitor based on hydrated ruthenium oxide (RuO2.xH2O) are presented. The electrochemical capacitor cell is based on three designs approaches: active surface enhancement via corrugations, the use of an ultra-thin self assembled dielectric implemented with hydrated Ruthenium oxide and activated carbon powders in combination with sulfuric acid and the fusion of both processes. We address the key components of the electrochemical cell (i) packaging,; (ii) the methodology of incorporating sulfuric acid and the various powders, and (iii) the deposition technique for the powder. The powder composition was varied to establish its effect on the overall capacitance. Mixing RuO2.xH2O and AC yielded devices with the greatest capacitance value, whereas devices containing only one of the two components had capacitance values lower by a factor of 10-50. The devices have capacitance values as large as 50 mF/cm2 per plate pair.

Two approaches to achieving reduced-defect active regions in III-N devices are discussed - confined epitaxy and heteroepitaxy on step-free SiC surfaces. In confined epitaxy, sapphire substrates (either GaN coated or not) are patterned with a dielectric mask and then III-N device structures are selectively and vertically grown in the openings using metalorganic chemical vapor deposition (MOCVD). In heteroepitaxy on step-free SiC surfaces, SiC mesas are created that have surfaces completely free of atomic steps and then used as substrates for conventional MOCVD III-N growth. In both approaches significant reductions in extended defect densities (10-100x) are observed and manifest in improved electroluminescence efficiency of UV emitters and leakage currents in UV detectors. Extensions of these efforts and other structural characterization results will be presented. Modeling results suggesting directions for future efforts will also be discussed.