Fabrication of Macroporous on No-Mask Silicon Substrate for Application to Microsystems

2008 ◽  
Author(s):  
Gyoko Nagayama ◽  
Ryuji Ando ◽  
Kei Muramatsu ◽  
Takaharu Tsuruta
Keyword(s):  
Fuel Cell ◽  
Porous Silicon ◽  
Pore Size ◽  
Silicon Wafer ◽  
Silicon Substrate ◽  
Electrochemical Etching ◽  
Cell System ◽  
Back Side ◽  
Ambient Conditions ◽  
Anodic Etching

We applied the anodic etching (i. e. photo assisted electrochemical etching) to the n type silicon substrate of orientation (100) without masking to fabricate macropores penetrated Si substrate. The anodic etching conditions of the macroporous formation were discussed and the effects of the resistivity, voltage, current density, electrolyte concentration and illumination etc. on the pore size and the porosity were investigated. The pores in high aspect ratio through the cross section of the silicon wafer were obtained with polishing and RIE (reactive ion etching) from the back side. It is found that the pore size at the back side is about 1.5 to 2 times larger than that of the front side. Also, as one example of the applications of porous silicon to microsystems, we demonstrate the results obtained in a micro fuel cell system using a porous silicon membrane (PSM). The PSM was fabricated by a porous silicon wafer which was filled with Nafion dispersion solution with ultrasonic vibrations. It was used as a proton conduction membrane by assembling into the H2 / air feed fuel cell at ambient conditions using conventional electrodes. We found that the Nafion filled PSM worked well and a maximum power density of 89.2 mW/cm2 were achieved under the flow rate of 100ml/min for H2 and 200ml/min for air.

Application of Porous Silicon on the Gas Diffusion Layer of Micro Fuel Cells

2007 ◽  
Vol 364-366 ◽  
pp. 849-854 ◽  
Author(s):  
Chi Yuan Lee ◽  
Shuo Jen Lee ◽  
Ching Liang Dai ◽  
Chih Wei Chuang
Keyword(s):  
Fuel Cell ◽  
Porous Silicon ◽  
Silicon Wafer ◽  
Diffusion Layer ◽  
Electrochemical Etching ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Pt Catalyst ◽  
Fuel Channel ◽  
Set Up

This investigation utilizes porous silicon as the gas diffusion layer (GDL) in a micro fuel cell. Pt catalyst is deposited on the surface of, and inside the porous silicon, to improve the performance of a fuel cell, and the Pt metal that remains on the rib is used to form a micro thermal sensor in a single lithographic process. Porous silicon with Pt catalyst replaces traditional GDL, and the relationships between porosity and pore diameter, and the performance of the fuel cell are discussed. In this work, electrochemical etching technology is employed to form porous silicon to replace the gas diffusion layer of a fuel cell. This work focuses on porous silicon with dimensions of tens of micrometers. Porous silicon was applied to the gas diffusion layer of a micro fuel cell. Boron-doped 20 '-cm n-type (100)-oriented doubly polished silicon wafer was used on both sides. The process is performed to etch a fuel channel on one side of a silicon wafer, and then electrochemical etching was adopted to form porous silicon on the other side to fabricate one silicon wafer that combines porous silicon with a fuel channel on a silicon wafer to minimize a fuel cell. The principles on which the method is based, the details of fabrication flows, the set-up and the experimental results are all presented.

Development of Fuel Cell System Control for Sub-Zero Ambient Conditions

2017 ◽  
Author(s):  
Tsuyoshi Maruo ◽  
Masashi Toida ◽  
Tomohiro Ogawa ◽  
Yuji Ishikawa ◽  
Hiroyuki Imanishi ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Cell System ◽  
System Control ◽  
Fuel Cell System ◽  
Ambient Conditions

Fabrication of Miniature Silicon Wafer Fuel Cells Using Micro Fabrication Technologies

2003 ◽  
Author(s):  
Jingrong Yu ◽  
Ping Cheng ◽  
Zhiqi Ma ◽  
Baolian Yi
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Silicon Wafer ◽  
Membrane Electrode ◽  
Silicon Substrates ◽  
Ambient Conditions ◽  
Micro Fabrication ◽  
Novel Structure ◽  
Electrode Assemblies ◽  
In Series

The fabrication of miniature silicon wafer fuel cells by micro-fabrication technologies and their performance evaluation are presented in this paper. Various thickness of Nafion membranes, such as Nafion 117, 115, and 112, were tested as electrolytes in a miniature single cell operating with dry H2/O2. Among these membranes, Nafion 112 (with the thinnest thickness) gave the best performance of 92.2 mW/cm2 at 250mA/cm2. In order to enhance the output voltage of the fuel cell, a miniature twin-fuel-cell was fabricated in series using two membrane-electrode-assemblies of Nafion 112 membrane sandwiched between two silicon substrates. The novel structure of the miniature twin-fuel-cell is that the electricity interconnect from the cathode of one cell to the anode of another cell is made on the same plane. The interconnect is fabricated by sputtering a layer of gold on the top of the silicon wafer. Silicon dioxide is deposited on the silicon wafer adjacent to the gold layer to prevent short-circuiting between the twin-cells. At ambient conditions, the measured peak power densities of the miniature twin-fuel-cell operating with H2/O2 and 1.5M methanol/O2, are 190.4mW/cm2 and 15.4mW/cm2, respectively.

Luminescence Activation of Porous Silicon by Post-Anodization Treatment

1992 ◽  
Vol 283 ◽  
Author(s):  
A. Kux ◽  
F. Muller ◽  
F. Koch
Keyword(s):  
Particle Size ◽  
Chemical Composition ◽  
Porous Silicon ◽  
Depth Distribution ◽  
Electrochemical Etching ◽  
Relative Importance ◽  
Porous Si ◽  
Ambient Conditions ◽  
Photochemical Etching ◽  
P Type

ABSTRACTWe prepare “nonluminescing” porous Si by electrochemical etching (50 mA/cm2 in 50% HF diluted 1:1 with ethanol) of 1 Ω(100) p-type wafers in the absence of light in order to study the subsequent luminescence activation by postprocessing. The treatments are: photochemical etching, ageing under ambient conditions, thermal oxidation. The study reveals remarkable inhomogeneities in the depth distribution of the luminescence and allows us to comment on the relative importance of particle size, spin density and chemical composition for the luminescence.

3-Mercaptopropionic Acid modified Porous Silicon Substrate used in Hyperammonemia

2007 ◽  
Vol 1063 ◽  
Author(s):  
Dong-hwa Yun ◽  
Jun-Hyoung Chang ◽  
Woo-Jin Lee ◽  
Suk-In Hong
Keyword(s):  
Porous Silicon ◽  
Silicon Substrate ◽  
Mechanical Stability ◽  
Electrochemical Etching ◽  
Covalent Binding ◽  
Self Assembled Monolayer ◽  
Long Time ◽  
Porous Silicon Substrate ◽  
Membrane Adhesion ◽  
Low Sensitivity

ABSTRACTAmperometric urea sensor is more suitable than optical and potentiometric urea sensor to diagnose hyperammonemia. However, because sensitivity in low concentration decreases remarkably, despite amperometric urea sensor has been studied for a long time it has not been applied for clinical diagnosis. In this paper, a new structure for an amperometric urea sensor was fabricated by MEMS, electrochemical etching, and electrostatic covalent binding techniques. Until now most amperometric urea sensors have had a membrane fixed on top of the transducer. That method often leads to malfunction of the sensor, arising from problems such as inadequate membrane adhesion, insufficient mechanical stability, and low sensitivity. To solve these kinds of problems, urease (Urs) was immobilized by electrostatic covalent binding method on the porous silicon (PSi) substrate coated self-assembled monolayer (SAM). Electrostatic covalent binding method was used to keep anisotropic orientation of urease on SAM.

A Study on Michanism of VisibLe Luminescence From Fbrous SiLicon

1993 ◽  
Vol 298 ◽  
Author(s):  
Zhou Yongdong ◽  
Jin Yixin ◽  
Ning Yongqiang ◽  
Yuan Linshan
Keyword(s):  
Surface Layer ◽  
Porous Silicon ◽  
Visible Light ◽  
Silicon Wafer ◽  
Silicon Substrate ◽  
Photoelectron Spectroscopy ◽  
Crystalline Silicon ◽  
Quantum Confinement Effect ◽  
Visible Luminescence ◽  
Fluorescent Powder

AbstractThe efficient visible tight emitting porous silicon was made using the standard method of anodic oxidation. The characteristic photoluminescence spectra and Raman Scattering spectra of the porous silicon were obtained. A kind of stable yellow powder (not the fragments of the porous silicon thin film the porous structure was still on the crystalline silicon substrate) was taken off from the visible light emitting porous silicon with nonchemical method. The powder can not dissolve in water, alcohol, acetone and some other common solvents, and it still emits efficient visible light after further grinding. The PL spectrum of the powder shows the same peak position, the same shape and the same FW-M as that of the porous silicon wafer. The microstructure of the porous silicon wafer and the microscopic shape of thepowder were studied using the scanningelectron microscopy (SEM) The X–ray photoelectron spectroscopy MSP) shows that the fluorescent powder in the surface layer of the porous silicon is composed of many kinds of elements, such as Si, Q a N and so on. The Si content is only 50% or less in the surface layer of porous silicon. The above–mentioned experiments were performed again on the unpolished surface of the single crystal silicon substrate. So we suggest that the visible luminescence of the porous silicon is from the fluorescent powder maybe not due to the quantum confinement effect in the nm–scate crystalline silicon pillars.

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