Transparent nanometric organic luminescent films as UV-active components in photonic structures

A new kind of visible-blind organic thin-film material, consisting of a polymeric matrix with a high concentration of embedded 3-hydroxyflavone (3HF) dye molecules, that absorbs UV light and emits green light is presented. The thin films can be grown on sensitive substrates, including flexible polymers and paper. Their suitability as photonic active components photonic devices is demonstrated. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Dye-Based Photonic Sensing Systems

[EN] We report on dye-based photonic sensing systems which are fabricated and packaged at wafer scale. For the first time luminescent organic nanocomposite thin-films deposited by plasma technology are integrated in photonic sensing systems as active sensing elements. The realized dye-based photonic sensors include an environmental NO2 sensor and a sunlight ultraviolet light (UV) A + B sensor. The luminescent signal from the nanocomposite thin-films responds to changes in the environment and is selectively filtered by a photonic structure consisting of a Fabry Perot cavity. The sensors are fabricated and packaged at wafer-scale, which makes the technology viable for volume manufacturing. Prototype photonic sensor systems have been tested in real-world scenarios.The authors thank the EU (Phodye Strep Project 033793 and ERC Starting Grant M&M's 277879), and the Spanish Ministry of Economy and Competitiveness (MAT-2010-21228) and Junta de Andalucia (P09-TEP-5283) for financial support.Aparicio, F.; Alcaire, M.; González-Elipe, A.; Barranco, A.; Holgado, M.; Casquel, R.; Sanza, F.... (2016). Dye-Based Photonic Sensing Systems. Sensors and Actuators B Chemical. 228:649-657. https://doi.org/10.1016/j.snb.2016.01.092S64965722

Wafer-level vacuum packaging enabled by plastic deformation and low-temperature welding of copper sealing rings with a small footprint

Wafer-level vacuum packaging is vital in the fabrication of many microelectromechanical systems (MEMS) devices and enables significant cost reduction in high-volume MEMS production. In this paper, we propose a low-temperature wafer-level vacuum packaging method based on plastic deformation and low-temperature welding of copper sealing rings with a small footprint. A device wafer with copper ring structures and a cap wafer with corresponding metalized grooves are placed inside a vacuum chamber and pressed together at a temperature of 250 ̊C, resulting in low-temperature welding of the copper, and thus, hermetic sealing of the cavities enclosed by the sealing rings. The vacuum pressure inside the fabricated cavities 146 days after bonding was measured using residual gas analysis to be as low as 2.6×10-2 mbar. Based on this value, the leak rate is calculated to be smaller than 3.6×10-16 mbarL/s using the most conservative assumptions, demonstrating the excellent hermeticity of the seals. Shear testing was used to demonstrate that the seals are mechanically stable with over 90 MPa in shear strength for 5.2 μm-high Cu sealing rings with widths down to 8 μm. The reported method is potentially compatible with complementary metaloxide-semiconductor (CMOS) substrates and may be applied to vacuum packaging of 3-D heterogeneously integrated MEMS on state-of-the-art CMOS substrates.QC 20170516When citing this work, please cite the original published paper.</p

A single-lithography SOI rib waveguide sensing circuit with apodized low back-reflection surface grating fiber coupling

We present a single-lithography Mach-Zehnder interferometer sensor circuit, with integrated low back-reflection input and output grating couplers. The low back-reflection is accomplished by a duty cycle apodization optimized for coupling light between single-mode silica fibers and the nanometric silicon-on-insulator (SOI) rib-waveguides. We discuss the design, fabrication, and characterization of the circuit. The apodization profile of the gratings is algorithmically generated using eigenmode expansion based simulations and the integrated waveguides, splitters, and combiners are designed using finite element simulations. The maximum simulated coupling efficiencies of the gratings are 70% and the multimode interference splitters and combiners have a footprint of only 19.2ￜ4.5 ￜm2. The devices are fabricated on an SOI wafer with a 220 nmdevice layer and 2 ￜm buried oxide, by a single electron beam lithography and plasma etching. We characterize the devices in the wavelength range from 1460-1580 nm and show a grating pass-band ripple of only 0.06 dB and grating coupling efficiency of 40% at 1530 nm. The integrated Mach-Zehnder interferometer has an extinction ratio of -18 dB at 1530 nm and between -13 and -19 dB over the whole 1460-1580 nm range.QC 20120612Cell-Rin

Narrow footprint copper sealing rings for low-temperature hermetic wafer-level packaging

This paper reports a narrow footprint sealing ring design for low-temperature, hermetic, and mechanically stable wafer-level packaging. Copper (Cu) sealing rings that are as narrow as 8 μm successfully seal the enclosed cavities on the wafers after bonding at a temperature of 250 °C. Different sealing structure designs are evaluated and demonstrate excellent hermeticity after 3 months of storage in ambient atmosphere. A leak rate of better than 3.6×10'16 mbarL/s is deduced based on results from residual gas analysis measurements. The sealing yield after wafer bonding is found to be not limited by the Cu sealing ring width but by a maximum acceptable wafer-to-wafer misalignment.QC 20171215</p

College Choice and Subsequent Earnings: Results Using Swedish Sibling Data

Using data on 19,000 whole siblings, it is shown that earnings vary significantly among students who have graduated from different colleges. The cross-section estimates are up to twice the within-family estimates, indicating that a regression estimator of college effects that does not adjust properly for family characteristics will overestimate the earnings premium of college. This study also shows that the effects of college choice vary between sisters and brothers and that there is a relationship between teacher quality and the college effects. These findings suggest that there is no straightforward interpretation of college in individual earnings equations. Copyright The editors of the "Scandinavian Journal of Economics", 2005 .