Etching Method of the Fabrication Optical Tapered Fiber and its Formula

2011 ◽  
Vol 145 ◽  
pp. 520-524 ◽  
Author(s):  
Yan Tang Huang ◽  
Xiao Hua Wang ◽  
Ri Yan Bao
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Etching Rate ◽  
Fiber Surface ◽  
Optical Power ◽  
Etching Process ◽  
Etching Time ◽  
Mathematics Model ◽  
Tapered Fiber ◽  
Etching Method

Optical tapered fiber is one of the most high efficiency evanescent wave coupler for coupling light into and out the optical microcavity. We fabricated the tapered fiber with etching method in a designed groove with HF solution. This method was low cost, readily, and controllable. An etching groove had an oval in the middle and small V-shape towards both sides. HF solution was injected into the oval groove, while the deioned water was injected into the two V-grooves. Because of the solution diffusion, the etching rate was fast in the mid and decreased gradually towards both sides,the tapered fiber was fabricated. The optical power meter was monitoring the fiber transmission during the etching process. The transmission of the tapered fiber was 98%. We proposed a mathematics model to depict the etching process, containing the relationship between the diameter of tapered fiber and the concentration of the HF solution, the etching time, humidity, temperature. We supervised the optical intensity to deduce the tapered fiber diameter. Surface morphology with AFM was detected, the roughness of the tapered fiber surface is less than 1nm. As an evanescent coupler, we used the tapered fiber to transmit 980nm pump laser to couple to Er3+doped microsphere to stimulate 1557nm laser.

scholarly journals Dry Etching of Germanium with Laser Induced Reactive Micro Plasma

2021 ◽  
Author(s):  
Martin Ehrhardt ◽  
Pierre Lorenz ◽  
Jens Bauer ◽  
Robert Heinke ◽  
Mohammad Afaque Hossain ◽  
...  
Keyword(s):  
Ion Beam ◽  
Etching Rate ◽  
Dry Etching ◽  
Etching Process ◽  
High Tech ◽  
Etching Time ◽  
High Quality ◽  
Machined Surface ◽  
Reactive Plasma ◽  
New Processing

AbstractHigh-quality, ultra-precise processing of surfaces is of high importance for high-tech industry and requires a good depth control of processing, a low roughness of the machined surface and as little as possible surface and subsurface damage but cannot be realized by laser ablation processes. Contrary, electron/ion beam, plasma processes and dry etching are utilized in microelectronics, optics and photonics. Here, we have demonstrated a laser-induced plasma (LIP) etching of single crystalline germanium by an optically pumped reactive plasma, resulting in high quality etching. A Ti:Sapphire laser (λ = 775 nm, EPulse/max. = 1 mJ, t = 150 fs, frep. = 1 kHz) has been used, after focusing with a 60 mm lens, for igniting a temporary plasma in a CF4/O2 gas at near atmospheric pressure. Typical etching rate of approximately ~ 100 nm / min and a surface roughness of less than 11 nm rms were found. The etching results were studied in dependence on laser pulse energy, etching time, and plasma – surface distance. The mechanism of the etching process is expected to be of chemical nature by the formation of volatile products from the chemical reaction of laser plasma activated species with the germanium surface. This proposed laser etching process can provide new processing capabilities of materials for ultra—high precision laser machining of semiconducting materials as can applied for infrared optics machining.

scholarly journals A Facile, Low-Cost Plasma Etching Method for Achieving Size Controlled Non-Close-Packed Monolayer Arrays of Polystyrene Nano-Spheres

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 605 ◽  
Author(s):  
Yun Chen ◽  
Dachuang Shi ◽  
Yanhui Chen ◽  
Xun Chen ◽  
Jian Gao ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Silicon Nanowires ◽  
High Frequency ◽  
Low Cost ◽  
Etching Rate ◽  
Low Frequency ◽  
Etching Time ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Etching System

Monolayer nano-sphere arrays attract great research interest as they can be used as templates to fabricate various nano-structures. Plasma etching, and in particular high-frequency plasma etching, is the most commonly used method to obtain non-close-packed monolayer arrays. However, the method is still limited in terms of cost and efficiency. In this study, we demonstrate that a low frequency (40 kHz) plasma etching system can be used to fabricate non-close-packed monolayer arrays of polystyrene (PS) nano-spheres with smooth surfaces and that the etching rate is nearly doubled compared to that of the high-frequency systems. The study reveals that the low-frequency plasma etching process is dominated by a thermal evaporation etching mechanism, which is different from the atom-scale dissociation mechanism that underlines the high-frequency plasma etching. It is found that the polystyrene nano-sphere size can be precisely controlled by either adjusting the etching time or power. Through introducing oxygen as the assisting gas in the low frequency plasma etching system, we achieved a coalesced polystyrene nano-sphere array and used it as a template for metal-assisted chemical etching. We demonstrate that the method can significantly improve the aspect ratio of the silicon nanowires to over 200 due to the improved flexure rigidity.

scholarly journals Design and Fabrication of Double-Layer Crossed Si Microchannel Structure

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1557
Author(s):  
Yipeng Wang ◽  
Weijian Zhou ◽  
Tieying Ma
Keyword(s):  
Double Layer ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Single Layer ◽  
Channel Structure ◽  
Etching Time ◽  
Etching Method ◽  
Straight Line ◽  
Root Cutting ◽  
Pass Through

A four-step etching method is used to prepare the double-layer cross Si microchannel structure. In the first etching step, a <100> V-groove structure is etched on (100) silicon, and the top channel is formed after thermal oxidation with the depth of the channel and the slope of its sidewall being modulated by the etching time. The second etching step is to form a sinking substrate, and then the third step is to etch the bottom channel at 90° (<100> direction) and 45° (<110> direction) with the top channel, respectively. Hence, the bottom channel on the sink substrate is half-buried into the top channel. Undercut characteristic of 25% TMAH is used to perform the fourth step, etching through the overlapping part of the two layers of channels to form a double-layer microchannel structure. Different from the traditional single-layer microchannels, the double-layer crossed microchannels are prepared by the four-step etching method intersect in space but are not connected, which has structural advantages. Finally, when the angle between the top and bottom is 90°, the root cutting time at the intersection is up to 6 h, making the width of the bottom channel 4–5 times that of the top channel. When the angle between the top and bottom is 45°, the root cutting time at the intersection is only 4 h, and due to the corrosion along (111), the corrosion speed of the sidewall is very slow and the consistency of the width of the upper and lower channels is better than 90° after the end. Compared with the same-plane cross channel structure, the semiburied microchannel structure avoids the V-shaped path at the intersection, and the fluid can pass through the bottom channel in a straight line and cross with the top channel without overlapping, which has a structural advantage. If applied to microfluidic technology, high-efficiency delivery of two substances can be carried out independently in the same area; if applied to microchannel heat dissipation technology, the heat conduction area of the fluid can be doubled under the same heat dissipation area, thereby increasing the heat dissipation efficiency.

scholarly journals Optimization of KOH etching process for MEMS square diaphragm using response surface method

2019 ◽  
Vol 15 (1) ◽  
pp. 113 ◽  
Author(s):  
Norliana Yusof ◽  
Badariah Bais ◽  
Burhanuddin Yeop Majlis ◽  
Norhayati Soin ◽  
Jumril Yunas
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
Process Parameters ◽  
Numerical Study ◽  
Etching Rate ◽  
Wet Etching ◽  
Etching Process ◽  
Etching Time ◽  
Surface Method ◽  
Koh Etching

<em><span>KOH wet etching is widely used in realizing MEMS diaphragm due to its low cost, safe and easy handling. However, wet etching process parameters need to be studied thoroughly in order to realize the desired shape and size of MEMS devices. This paper presents the numerical study and optimization of KOH etching process parameters using the response surface method (RSM). Face central composite design (FCC) of RSM was employed as the experimental design to analyze the result and generate a mathematical prediction model. From the analysis, the temperature was identified as the most significant process parameter that affects the etching rate, thus affecting the thickness and size of the diaphragm. The results of RSM prediction for optimization were applied in this study. Particularly, 45% of KOH concentration, temperature of 80°C, 1735 µm2 of mask size, and 7.2 hours of etching time were implemented to obtain a square MEMS diaphragm with thickness of 120 µm and size of 1200 µm2. The results of RSM based optimization method for KOH wet etching offers a quick and effective method for realizing a desired MEMS device.</span></em>

scholarly journals Texture-Etched SnO2Glasses Applied to Silicon Thin-Film Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Bing-Rui Wu ◽  
Sin-Liang Ou ◽  
Shih-Yung Lo ◽  
Hsin-Yuan Mao ◽  
Jhen-Yu Yang ◽  
...  
Keyword(s):  
Thin Film ◽  
Surface Roughness ◽  
Solar Cells ◽  
Light Scattering ◽  
Etching Rate ◽  
Etching Process ◽  
Thin Film Solar Cells ◽  
Etching Time ◽  
Silicon Thin Film ◽  
Mixture Ratio

Transparent electrodes of tin dioxide (SnO2) on glasses were further wet-etched in the diluted HCl:Cr solution to obtain larger surface roughness and better light-scattering characteristic for thin-film solar cell applications. The process parameters in terms of HCl/Cr mixture ratio, etching temperature, and etching time have been investigated. After etching process, the surface roughness, transmission haze, and sheet resistance of SnO2glasses were measured. It was found that the etching rate was increased with the additions in etchant concentration of Cr and etching temperature. The optimum texture-etching parameters were 0.15 wt.% Cr in 49% HCl, temperature of 90°C, and time of 30 sec. Moreover, silicon thin-film solar cells with the p-i-n structure were fabricated on the textured SnO2glasses using hot-wire chemical vapor deposition. By optimizing the texture-etching process, the cell efficiency was increased from 4.04% to 4.39%, resulting from the increment of short-circuit current density from 14.14 to 15.58 mA/cm2. This improvement in cell performances can be ascribed to the light-scattering effect induced by surface texturization of SnO2.

scholarly journals Enhanced Efficiency of Graphene-silicon Schottky Junction Solar Cell through Pyramid Arrays Texturation

2021 ◽  
Author(s):  
Cheng Li ◽  
Yichen Ma ◽  
Xiyao Zhang ◽  
Xiuhua Chen ◽  
Fengshuo Xi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Large Scale ◽  
High Efficiency ◽  
Low Cost ◽  
Surface Texturing ◽  
Schottky Junction ◽  
Etching Time ◽  
Uniform Size ◽  
Si Solar Cells ◽  
New Strategy

Abstract Graphene/silicon (Gr/Si) Schottky junction solar cells have attracted extensive research interest due to their simple structure and potential low-cost. Surface texturing is an important part of high-efficiency solar cells. In this paper, the effects of TMAH concentration, IPA concentration and etching time on the structure and anti-reflection ability of silicon pyramid array (SiPa) were systematically studied to obtain uniform and reliable pyramid array. Under the optimized conditions, a large scale SiPa with uniform size distribution was obtained and applied to Gr/Si solar cells. The results show that the TMAH etched SiPa has a better Schottky junction contact between graphene and the SiPa surface, and the SiPa can further improves the ability of collecting photogenerated carriers. Compared with Gr/Si solar cells, the power conversion efficiency (PCE) of Gr/SiPa device is 1.66 times higher than that of Gr/Si solar cells. Finally, Gr/SiPa devices with PCE of 5.67% is successfully obtained by HNO3 doping. This work proposes a new strategy for TMAH etching SiPa to improve the performance of Gr/Si solar cells.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

Contradiction Analysis and Solution in the R&D of High-Power Solar LED Street Lamp Controller

2019 ◽  
Vol 12 (1) ◽  
pp. 12-19
Author(s):  
Zhengwang Xu ◽  
Wei Mei ◽  
Jiaqi Yu ◽  
Jiarui Zhang ◽  
Yuchun Yi ◽  
...  
Keyword(s):  
Power Supply ◽  
High Efficiency ◽  
Low Cost ◽  
Solar Panel ◽  
Battery Voltage ◽  
Supply Circuit ◽  
Led Light ◽  
Power Supply Circuit ◽  
Side Mode ◽  
Dual Power

As being restricted by factors such as cost, efficiency and size, the development of high-power solar LED street light controller is faced with plenty of difficulties. In case that a structure of two independent DC/DC is applied as the main circuit, it has to face problems such as large size and high cost; in case of applying the bidirectional BUCK/BOOST circuit, it requires change-over switches to control the solar panel and LED light. As being restricted by withstanding voltage, on-resistance and cost, a PMOS device cannot be used as the change-over switch of solar panel and LED light. However, when being used as a change-over switch, an NMOS device must apply the low-side mode under which the negative ends of the mentioned three parts are cut off. In the condition of applying the low-side mode, a differential circuit must be used to detect the voltage of the solar panel. Furthermore, in order to make sure batteries can still be regularly charged after wearing out in daylight, the controller must be supplied with power through a dual power supply circuit that can obtain power from both the solar panel and the battery. The demander has a requirement on extremely low standby power consumption of the product, and thus it is necessary to minimize the circuit that is live while working in standby mode. Methods: The bidirectional BUCK/BOOST circuit structure is applied to the main circuit to realize a higher change-over efficiency while giving considerations to both cost and size. The NMOS device, model IRFB4410ZPBF, with a price of about three yuan, is used as the switching device, and the low-side mode is applied, that is the switches inserted in between negative end of the solar panel or LED light and that of the DC/DC circuit. The low-cost rail-to-rail operational amplifier LM358 is used to form a differential amplification circuit for detecting the voltage of the solar panel. A XL1509-12E1 chip that only costs 0.88 yuan/pc is selected as the main change-over chip for the power supply, which has realized the highly-efficient and low-cost change-over of the power supply. A dual power supply circuit and a step-down protective circuit are designed for the XL1509-12E1 change-over chip. By comparing solar panel voltage with battery voltage, the solar panel booting circuit is realized. Only when solar panel voltage is higher than battery voltage, does the system program start to power it up for running, so that the outage of most of the circuits of the system under standby mode does not consume energy. Furthermore, the solar panel voltage detecting circuit, the solar panel booting circuit and several return difference functions are corrected during system debugging. Results: The circuit board of the entire controller features small size, low cost and high efficiency. It measures about 100*62*18mm in size, costs about 60 yuan, and the charge/discharge change-over efficiency reaches up to over 95%. The controller has many functions: it is capable of operating within a large scope, in which, solar panel voltage is subject to 15~50V, LED light voltage is subject to 15~60V, battery voltage is subject to 10~35V and battery-end charge/discharge current is 10A; it is capable of adapting to monocrystalline silicon/multicrystalline silicon/thin-film and many other kinds of solar panels, as well as lithium/lead-acid and many other kinds of batteries; it is capable of detecting the conversion of day and night, automatically controlling charging and discharging and automatically making adaptive adjustment according to seasonal variations; the current to be consumed during standby will be maintained below 3mA, and thus the power consumption is extremely low. Conclusion: By selecting the bidirectional BUCK/BOOST circuit structure, applying low-side mode for switching of solar panel and LED light, using a differential circuit to detect solar panel voltage, using a low-cost DC/DC chip to realize power supply change-over, designing a dual power supply circuit, introducing solar panel booting circuit and other hardware design, as well as MPPT algorithm, state recognition and control, return difference control and other software design, a solar LED street light control product featuring small size, low cost, high efficiency and multiple functions is successfully developed.

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