Search results for "microfabrication"

Microfabrication of hybrid fluid membrane for microengines

2015

International audience; This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dyna…

Artificial dielectric optical structures: A challenge for nanofabrication

1998

Diffractive optical components can be made using multiple level kinoforms or single level artificial dielectric structures. The latter require the fabrication of pillars of equal depth but differing width and spacing. As a demonstration device, the diffractive optic equivalent of a wedge has been made in GaAs for use at 1.15 μm. The need for all pillars to have the same height was met by using a selective etch and a very thin etch-stop layer on AlGaAs. The experimental diffraction efficiency was 87.8%, among the best ever obtained and close to the theoretical maximum of 97.6%. © 1998 American Vacuum Society.

Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution: GaAs and InP, a striking contrast in surface chemistry

2019

In this study of nanoscale etching for state-of-the-art device technology, the importance of surface chemistry, in particular the nature of the surface oxide, is demonstrated for two III-V materials. Striking differences in etching kinetics were found for GaAs and InP in sulphuric and hydrochloric acidic solutions containing hydrogen peroxide. Under similar conditions, etching of GaAs was much faster, while the dependence of the etch rate on pH, and on H2O2 and acid concentrations also differed markedly for the two semiconductors. Surface analysis techniques provided information on the product layer present after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin st…

Effects of different etching strategies on the microtensile repair bond strength of beautifil II giomer material

2018

Background Considering the differences in the filler particles between giomer and conventional composite resins and the importance of these fillers in the repair bond strength, the aim was to evaluate the effects of different etching strategies with phosphoric acid (PA) and hydrofluoric acid (HF) on the microtensile repair bond strength (µTRBS) of giomer. Material and Methods Ten giomer blocks were randomly assigned into 10: 1) control; 2) 37%PA-20s; 3) 3%HF-20s; 4) 3%HF-120s; 5) 9.6%HF-20s; 6) 9.6%HF-120s; 7) 37%PA-20s + 3%HF-120s; 8) 37%PA-20s + 9.6%HF-120s; 9) 3%HF-120s + 37%PA-20s; 10) 9.6%HF-120s + 37%PA-20s. In all groups, the One-Step Plus bonding system was applied and the new giome…

Plasma Etching and Integration with Nanoprocessing

2009

This chapter introduces plasma etching—an extensive and perhaps the most widely used micro- and nanoprocessing method both in industry and in research and development laboratories worldwide. The emphasis is on the practical methods in plasma etching and reactive ion etching when used for submicron and nanoscale device fabrication. The principles of plasma etching and reactive ion etching equipment for sample fabrication will be introduced.

Microcavity Light Emitting Diodes Based on GaN membranes Grown by Molecular Beam Epitaxy on Silicon

2003

Resonant-cavity InGaN/GaN quantum well light emitting diodes have been fabricated. Nitride layers were grown by molecular beam epitaxy on Si (111). We fabricated the structures using a combination of Si substrate etching, GaN etching and dielectric (Ta2O5/SiO2) mirror deposition. The electroluminescence spectra show that the emission within the distributed Bragg reflector stop band is enhanced in the membrane microcavity. The cavity modes are broadened by some cavity length non-uniformity that is introduced when the GaN is back etched to adjust the cavity length. This process does not need any transfer on an intermediate host substrate and is fully compatible with large area semiconductor p…

2017

Significant progress in nonlinear and ultrafast optics has recently opened new and exciting opportunities for terahertz (THz) science and technology, which require the development of reliable THz sources, detectors, and supporting devices. In this work, we demonstrate the first solid-state technique for the coherent detection of ultra-broadband THz pulses (0.1–10 THz), relying on the electric-field-induced second-harmonic generation in a thin layer of ultraviolet fused silica. The proposed CMOS-compatible devices, which can be realized with standard microfabrication techniques, allow us to perform ultra-broadband detection with a high dynamic range by employing probe laser powers and bias v…

High-frequency filtering for low-temperature thermal transport studies in nanostructures

2012

Filtering of external unwanted RF-noise and thermal noise generated at the high-temperature parts of the measuring circuit is essential for successful measurements of thermal transport of nanostructures at low temperatures. This is because of thermal decoupling of the systems, i.e. the extreme weakness of thermal conduction at sub-Kelvin temperatures, leading easily to overheating even with excess power in sub pW range. We have started to improve the noise filtering in our cryogenic dilution refrigerators, which can reach a base temperature of ~ 50 mK. The miniature low-pass filters were made from special RF sealing compound Eccosorb CR124, stainless steel powder of grain size 50 micrometer…

ChemInform Abstract: Photoelectrochemical Study of Electrochemically Formed Semiconducting Yttrium Hydride (YH3-x).

2010

Abstract The first photoelectrochemical study of semiconducting YH 3− x films formed by etching bulk Y metal in 0.5 M H 2 SO 4 solution is reported. The formation of semiconducting hydride having an indirect optical band gap, E g opt , of about 2.35 eV is confirmed by in situ photocurrent spectroscopy. The photoelectrochemical behaviour of such a phase was investigated both in alkaline and in acidic solutions. The flat band potential was estimated to be U fb =−1.25 V/NHE, independent of pH.

A polarimetric sensor based on nanoporous free standing membranes

2012

A polarimetric sensor with state of the art sensitivity is developed using free standing porous silicon membranes. The use of an optimized etching receipt greatly reduces the pore roughness. Depolarization factors are thus limited and material birefringence is increased. Free standing membranes are fabricated in n-type substrates and characterized both from the optical and structural point of view. The proposed approach is fully CMOS compatible and can therefore pave the way to the development of cheap microarray that exploits multiplexing capabilities while keeping the amount of analyte required by the analysis down to the microliter level.