Fabrication process and power and lifetime characteristics of very-small-aperture laser

High output power very-small-aperture laser has been created on 650 nm edge emitting laser diodes. The far-field output power is 0.4 mW at the 25 mA driving current, and the highest output power exceeds 1 mW. The special fabrication process is described and the failure mechanism leading to the short lifetime of the devices is discussed.

Application of Wet Chemical Etching in Fabrication Process of GaAs/AlGaAs Quantum Dot Arrays

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Novel fabrication process of planar waveguides in rare-earth doped fluoroindate glasses

We report the successful fabrication of planar waveguides in rare-earth doped fluoroindate glass substrates. A new procedure for waveguide fabrication using a thermally evaporated AgF nonmetallic film was developed. The refractive index changes of more than 0.03, associated to low propagation losses achieved, open new perspectives and show the potentiality of using this glass family toward further developments in fabrication and design of integrated optical devices for optical communication wavelengths.© 1995 American Institute of Physics.

Fabrication process of Mo/Au TES at RT

We report on the fabrication details of TES based on Mo/Au bilayers. The Mo layer is deposited by radio frequency (RF) sputtering and capped with a sputter deposited thin Au protection layer. Afterwards, a second Au layer of suitable (lower) resistivity is deposited ex‐situ by e‐beam evaporation, until completion of the total desired Au thickness. The deposition was performed at room temperature (RT) on LPCVD Si3 N4 membranes. Such a deposition procedure is very reproducible and allow controlling the critical temperature (Tc) and normal electrical resistance (RN ) of the Mo/Au bilayer. The process is optimized to achieve low stress bilayers, thus avoiding the undesirable curvature of the membranes. Bilayers are patterned using photolithographic techniques and wet etching procedures. Mo superconducting paths are used to contact the Mo/Au bilayers, thus ensuring good electrical conductivity and thermal isolation. The entire fabrication process let to stable and reproducible sensors with required and tunable functional properties

Progress on optimization of the solar cell fabrication process by impurity-to-efficiency predictive simulator

To optimize the last high temperature step of a standard solar cell fabrication process (the contact cofiring step), the aluminium gettering is incorporated in the Impurity-to-Efficiency simulation tool, so that it models the phosphorus and aluminium co-gettering effect on iron impurities. The impact of iron on the cell efficiency will depend on the balance between precipitate dissolution and gettering. Gettering efficiency is similar in a wide range of peak temperatures (600-850 ºC), so that this peak temperature can be optimized favoring other parameters (e.g. ohmic contact). An industrial co-firing step can enhance the co-gettering effect by adding a temperature plateau after the peak of temperature. For highly contaminated materials, a short plateau (menor que 2 min) at low temperature (600 ºC) is shown to reduce the dissolved iron.

Fiber bragg gratings:advances in fabrication process and tools

Successful commercialization of a technology such as Fiber Bragg Gratings requires the ability to manufacture devices repeatably, quickly and at low cost. Although the first report of photorefractive gratings was in 1978 it was not until 1993, when phase mask fabrication was demonstrated, that this became feasible. More recently, draw tower fabrication on a production level and grating writing through the polymer jacket have been realized; both important developments since they preserve the intrinsic strength of the fiber. Potentially the most significant recent development has been femtosecond laser inscription of gratings. Although not yet a commercial technology, it provides the means of writing multiple gratings in the optical core providing directional sensing capability in a single fiber. Femtosecond processing can also be used to machine the fiber to produce micronscale slots and holes enhancing the interaction between the light in the core and the surrounding medium. © 2011 Bentham Science Publishers Ltd. All rights reserved.

Fiber bragg gratings:advances in fabrication process and tools

Successful commercialization of a technology such as Fiber Bragg Gratings requires the ability to manufacture devices repeatably, quickly and at low cost. Although the first report of photorefractive gratings was in 1978 it was not until 1993, when phase mask fabrication was demonstrated, that this became feasible. More recently, draw tower fabrication on a production level and grating writing through the polymer jacket have been realized; both important developments since they preserve the intrinsic strength of the fiber. Potentially the most significant recent development has been femtosecond laser inscription of gratings. Although not yet a commercial technology, it provides the means of writing multiple gratings in the optical core providing directional sensing capability in a single fiber. Femtosecond processing can also be used to machine the fiber to produce micronscale slots and holes enhancing the interaction between the light in the core and the surrounding medium. © 2011 Bentham Science Publishers Ltd. All rights reserved.

One step self-aligned multilayer patterning process for the fabrication of organic complementary circuits in combination with inkjet printing

Recent development of solution processable organic semiconductors delineates the emergence of a new generation of air-stable, high performance p- and n-type materials. This makes it indeed possible for printed organic complementary circuits (CMOS) to be used in real applications. The main technical bottleneck for organic CMOS to be adopted as the next generation organic integrated circuit is how to deposit and pattern both p- and n-type semiconductor materials with high resolutions at the same time. It represents a significant technical challenge, especially if it can be done for multiple layers without mask alignment. In this paper, we propose a one-step self-aligned fabrication process which allows the deposition and high resolution patterning of functional layers for both p- and n-channel thin film transistors (TFTs) simultaneously. All the dimensional information of the device components is featured on a single imprinting stamp, and the TFT-channel geometry, electrodes with different work functions, p- and n-type semiconductors and effective gate dimensions can all be accurately defined by one-step imprinting and the subsequent pattern transfer process. As an example, we have demonstrated an organic complementary inverter fabricated by 3D imprinting in combination with inkjet printing and the measured electrical characteristics have validated the feasibility of the novel technique. © 2012 Elsevier B.V. All rights reserved.

Fabrication and characterization of sub 100 nm period polymer gratings for photonics applications

We report on the fabrication of polymethylmethacrylate (PMMA) nanogratings on silicon (Si) and glass substrates using electron beam lithography technique. Various aspects of proximity corrections using Monte Carlo simulation have been discussed. The fabrication process parameters such as proximity gap of exposure, exposure dosage and developing conditions have been optimized for high-density PMMA nanogratings structure on Si and glass substrates. Electron beam exposure is adjusted in such a way that PMMA acts as a negative tone resist and at the same time resolution loss due to proximity effect is minimum. Both reflection and transmission-type, nanometre period gratings have been fabricated and their diffraction characteristics are evaluated.

Fabrication of back contacts using laser writer and photolithography for inscribing textured solar cells

Semiconductor fabrication process begins with photolithography. Preparing a photo mask is the key process step in photolithography. The photo mask was fabricated by inscribing patterns directly onto a soda lime glass with the help of a laser beam, as it is easily controllable. Laser writer LW405-A was used for preparing the mask in this study. Exposure wavelength of 405 nm was used, with which 1.2 mu m feature size can be written in direct write-mode over the soda lime glass plate. The advantage of using the fabricated mask is that it can be used to design back contacts for thin film Photovoltaic (PV) solar cells. To investigate the process capability of LW405-A, same pattern with different line widths was written on soda lime glass samples at different writing speeds. The pattern was inscribed without proximity effect and stitching errors, which was characterized using optical microscope and field emission scanning electron microscope (FE-SEM). It was proven that writing speed of a mask-writer is decided according to the intended feature size and line width. As the writing speed increases, the edges of the patterns become rougher due to uneven scattering of the laser beam. From the fabricated mask, the solar cell can be developed embedding both the contacts at the bottom layer, to increase the absorption of solar radiation on the top surface effectively by increasing light absorption area.

Fabrication and bio-functionalization of tetrahedral amorphous carbon thin films for bio sensor applications

Tetrahedral amorphous carbon (ta-C) thin films are a promising material for use as biocompatible interfaces in applications such as in-vivo biosensors. However, the functionalization of ta-C film surface, which is a pre-requisite for biosensors, remains a big challenge due to its chemical inertness. We have investigated the bio-functionalization of ta-C films fabricated under specific physical conditions through the covalent attachment of functional biomolecular probes of peptide nucleic acid (PNA) to ta-C films, and the effect of fabrication conditions on the bio-functionalization. The study showed that the functional bimolecular probes such as protected long-chain ω-unsaturated amine (TFAAD) can be covalently attached to the ta-C surface through a well-defined structure. With the given fabrication process, electrochemical methods can be applied to the detection of biomolecular interaction, which establishes the basis for the development of stable, label-free biosensors. © 2011 Elsevier B.V. All rights reserved.

Fabrication of microelectrodes deeply embedded in LiNbO3 using a femtosecond laser

We present a novel technique to fabricate deeply embedded microelectrodes in LiNbO3 using femtosecond pulsed laser ablation and selective electroless plating. The fabrication process mainly consists of four steps, which are (1) micromachining of microgrooves on the surface of LiNbO3 by femtosecond laser ablation; (2) formation of AgNO3 films on substrates; (3) scanning the femtosecond laser beam in the fabricated microgrooves for modi. cation of the inner surfaces; and (4) electroless copper plating. The void-free electroless copper plating is obtained with appropriate cross section of microgrooves and uniform initiation of the autocatalytic deposition on the inner surface of grooves. The dimension and shape of the microelectrodes could be accurately controlled by changing the conditions of femtosecond laser ablation, which in turn can control the distribution of electric field inside LiNbO3 crystal for various applications, opening up a new approach to fabricate three-dimensional integrated electro-optic devices. (C) 2008 Elsevier B. V. All rights reserved.

Compensation of reflectance response deviations of guided-mode resonant filters induced by overetching fabrication

Unless the fabrication error control is well treated, it easily causes overetched fabrication errors, which causes the resonant peak value deviation during the fabrication process of guided-mode resonant filters (GMRFs). Hence, the fabrication error control becomes a key point for improving the performance of GMRF. We find that, within the range of the groove depth from 93 to 105 nm, the relationship between the overetched error and the resonant peak value deviation is nearly linear, which means that we can compensate the reflectance response deviation and reduce the resonant peak value deviation by the method of covering the layer film on the GMRF. Simulation results show that the deviation is compensated perfectly by this way. (C) 2008 Optical Society of America