scholarly journals Low-cost photodetector architectures fabricated at room-temperature using nano-engineered silicon wafer and sol-gel TiO2 – based heterostructures

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debika Banerjee ◽  
Ivy M. Asuo ◽  
Alain Pignolet ◽  
Sylvain G. Cloutier
Keyword(s):  
Low Cost ◽  
Silicon Nanowire ◽  
Sol Gel ◽  
Nanowire Array ◽  
Device Fabrication ◽  
Visible Range ◽  
Ambient Conditions ◽  
Silicon Nanowire Arrays ◽  
External Bias ◽  
Wide Range

AbstractIn the last decades, significant research has been done on the nanocrystalline forms of titanium dioxide (TiO2). Amorphous TiO2 has not been studied intensively despite being significantly less expensive compared to crystalline TiO2. This study reveals significant improvement in UV-VIS photodetection properties from heterostructures fabricated in ambient environment using n-type silicon nanowire arrays and amorphous TiO2 sol-gel. Our ultra-low-cost UV-VIS photodetectors can cover a wide range of applications. We report fast rise/decay time constants of 0.23 ms/0.17 ms and high responsivity up-to 6.0 A/W in the UV and 25.0 A/W in the visible range under low (1 V) external bias. The large surface area due to the nanowire array architecture leads to 2 orders of magnitude enhancement in photo-response. Besides the final electrode deposition, the entire device fabrication is performed using low-cost, all solution-based methods in ambient conditions. These low-cost UV-Visible broadband photodetectors can potentially serve a wide range of applications.

Synthesis of Photosensitive Organic-Inorganic Hybrid Polymers via Anhydrous Sol-Gel Process for Integrated Optics

2003 ◽  
Vol 780 ◽  
Author(s):  
Xinshi Luo ◽  
Congji Zha ◽  
Barry Luther-Davies
Keyword(s):  
Low Cost ◽  
Sol Gel ◽  
Optical Loss ◽  
Hybrid Polymer ◽  
Optical Losses ◽  
Hybrid Polymers ◽  
Inorganic Hybrid ◽  
Wide Range ◽  
Integrated Optical ◽  
Sol Gel Process

AbstractPhotosensitive organic-inorganic hybrid polymers were synthesised for integrated optical and optoelectronic devices by a non-hydrous sol-gel process of hydrolysis/condensation of 3-methacryloxypropyltrimethoxysilane (MPS), diphenyldimethoxysilane (DPhDMS), and zirconium isopropoxide (TPZ) with boric acid under anhydrous conditions. The methacryl groups of MPS are UVpolymerizable, which are suitable for low cost fabrication of waveguides with a “UV write/develop” process. The incorporation of DPhDMS and TPZ was found useful in reducing the optical loss and in enhancing the thermostability of the polymer. The refractive index of the hybrid polymer is tuneable from 1.4950 to 1.5360 by variation of the ratio among MPS, DPhDMS and TPZ. Optical characterisation showed that the material has low optical losses at the telecommunications windows (0.16 dB/cm at 1310 nm and 0.4 dB/cm at 1550nm). The hybrid polymer also showed a low birefringence (1.2×10-4), a large thermo-optic (TO) coefficient (-2.77 ×10-4), and an outstanding linearity of dn/dT in a wide range of temperature (from 25 °C to 200 °C). Waveguides forming ability for the hybrid polymer with UV imprinting was also demonstrated.

Dye-Improved Optical Absorption of Vertically Aligned Silicon Nanowire Arrays Synthesized by Electroless Etching of Silicon Wafer

2014 ◽  
Vol 895 ◽  
pp. 200-203 ◽  
Author(s):  
Hui Chiang Teoh ◽  
Sabar Derita Hutagalung
Keyword(s):  
Silicon Nanowires ◽  
High Performance ◽  
Silicon Nanowire ◽  
Incident Light ◽  
Electroless Etching ◽  
Dye Sensitized ◽  
Silicon Nanowire Arrays ◽  
Wide Range ◽  
Vertically Aligned ◽  
Si Wafer

Silicon nanowires (SiNWs) are important candidate for high performance electronic and optoelectronic devices due to their unique structures, electrical and optical properties. SiNWs were fabricated by silver-assisted electroless etching of Si wafer. Vertically aligned SiNW arrays with length about 8.75 μm and diameter of less than 90 nm have been fabricated. The reflectance of SiNWs without dye (12%) is greatly lower compared to bare Si wafer (25%). Therefore, SiNWs on Si substrate can be used as a good anti-reflection layer for a wide range of incident light. The reflectance of dye-sensitized SiNWs with red, green and blue dyes is 7%, 5.5%, and 5% respectively. The results confirmed that the reflectance of SiNWs with dye is much lower compared to SiNWs without dye and bare Si wafer. It was proven that dye on SiNWs can be used to reduce the reflectance (improved absorption) about 40% compared to SiNWs without dye.

scholarly journals Large scale low cost fabrication of diameter controllable silicon nanowire arrays

2014 ◽  
Vol 25 (25) ◽  
pp. 255302 ◽  
Author(s):  
Leimeng Sun ◽  
Yu Fan ◽  
Xinghui Wang ◽  
Rahmat Agung Susantyoko ◽  
Qing Zhang
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Silicon Nanowire ◽  
Nanowire Arrays ◽  
Silicon Nanowire Arrays

scholarly journals Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors

2014 ◽  
Vol 5 ◽  
pp. 964-972 ◽  
Author(s):  
Tomi Roinila ◽  
Xiao Yu ◽  
Jarmo Verho ◽  
Tie Li ◽  
Pasi Kallio ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Leakage Current ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Low Cost ◽  
Silicon Nanowire ◽  
Binary Sequence ◽  
Practical Applications ◽  
Frequency Domain Methods ◽  
Wide Range

Silicon nanowire-based field-effect transistors (SiNW FETs) have demonstrated the ability of ultrasensitive detection of a wide range of biological and chemical targets. The detection is based on the variation of the conductance of a nanowire channel, which is caused by the target substance. This is seen in the voltage–current behavior between the drain and source. Some current, known as leakage current, flows between the gate and drain, and affects the current between the drain and source. Studies have shown that leakage current is frequency dependent. Measurements of such frequency characteristics can provide valuable tools in validating the functionality of the used transistor. The measurements can also be an advantage in developing new detection technologies utilizing SiNW FETs. The frequency-domain responses can be measured by using a commercial sine-sweep-based network analyzer. However, because the analyzer takes a long time, it effectively prevents the development of most practical applications. Another problem with the method is that in order to produce sinusoids the signal generator has to cope with a large number of signal levels. This may become challenging in developing low-cost applications. This paper presents fast, cost-effective frequency-domain methods with which to obtain the responses within seconds. The inverse-repeat binary sequence (IRS) is applied and the admittance spectroscopy between the drain and source is computed through Fourier methods. The methods is verified by experimental measurements from an n-type SiNW FET.

scholarly journals Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

2015 ◽  
Vol 51 (53) ◽  
pp. 10742-10745 ◽  
Author(s):  
Xiao-Qing Bao ◽  
M. Fatima Cerqueira ◽  
Pedro Alpuim ◽  
Lifeng Liu
Keyword(s):  
Hydrogen Evolution ◽  
Low Cost ◽  
Silicon Nanowire ◽  
Hollow Spheres ◽  
Nanowire Arrays ◽  
Photoelectrochemical Performance ◽  
Solar Hydrogen ◽  
Cobalt Phosphide ◽  
Silicon Nanowire Arrays ◽  
Earth Abundant

Low-cost photocathodes consisting of silicon nanowire arrays coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts are fabricated, which exhibit good photoelectrochemical performance toward the solar-driven H2 evolution.

A Novel and Simple Electrochemical Glucose Biosensor Based on a Silicon Nanowire Array Electrode

2014 ◽  
Author(s):  
Che-Wei Hsu ◽  
Wen-Chao Feng ◽  
Kang J. Chang ◽  
Gou-Jen Wang
Keyword(s):  
Low Cost ◽  
Silicon Nanowire ◽  
Nanowire Array ◽  
High Sensitivity ◽  
Glucose Biosensor ◽  
Glucose Detection ◽  
Redox Peak ◽  
Array Electrode ◽  
Silicon Nanowire Array ◽  
Very High

In this study, a novel and simple electrochemical glucose biosensor based on a silicon nanowire array (SNA) electrode was proposed. Metal-assisted etching (MAE) method using an AgNO3 and HF mixing solution as the etchant was employed to grow the silicon nanowire array (SNA) electrode. A thin gold shell is then sputtered over each silicon nanowire. Potassium ferricyanide, glucose oxidase (GOx), and a Nafion thin film were then sequentially coated onto the fabricated SNA for glucose detection. The processing time of the MAE and sputtering as well as the GOx concentration were optimized in terms of the redox peak currents of the SNA electrode. Compared with the corresponding plane gold electrode, the effective sensing area of the synthesized SNA electrode was measured to be 6.12 folds. Actual glucose detections demonstrated that the proposed SNA array electrode could operate in a linear range of 0.55 mM-11.02 mM and a very high sensitivity of 346 μA mM−1 cm−2. The proposed SNA electrode based glucose biosensor possesses advantages of simple fabrication process, low cost, and high sensitivity. It is feasible for future clinical applications.

Tungsten Oxide (WO3) Films Prepared by Sol-Gel Spin-Coating Technique

2018 ◽  
Vol 280 ◽  
pp. 71-75 ◽  
Author(s):  
B. Wen Cheun Au ◽  
Kah Yoong Chan ◽  
Wai Leong Pang ◽  
Chu Liang Lee ◽  
Abd Hamid Mustafa
Keyword(s):  
Film Thickness ◽  
Tungsten Oxide ◽  
Indium Tin Oxide ◽  
Spin Coating ◽  
Sol Gel ◽  
Optical Transmittance ◽  
Visible Range ◽  
Smart Windows ◽  
Wide Range ◽  
Coating Method

Tungsten oxide (WO3) is a transition metal oxide with a wide range of applications such as displays, rear-view mirrors, electrochromic (EC) smart windows and gas sensors. Many techniques were adopted for the fabrication of WO3, namely magnetron sputtering, spray pyrolysis and sol-gel synthesis techniques. In this work, WO3films were deposited on indium tin oxide (ITO) coated glasses by sol-gel spin-coating method. The film thickness was varied by depositing different number of layers. The WO3film thickness and optical transmittance were determined using step profilometer and ultraviolet-visible (UV-Vis) spectrophotometer, respectively. WO3film thicknesses increased from 38 nm to 606 nmwith increasing number of deposited layers.The optical transmittance of the WO3films in visible range decreased with increasing film thickness. The optical transmittance were at least 70 % up to 10 deposited layers.WO3is a promising EC material in the application ofEC devices (ECDs).The application of WO3in the EC devices will be discussed.

Influences of Stirring Speed and Post Annealing Temperature on the Properties of Zinc Oxide Colloid Prepared by Sol-Gel Spin Coating Method

2016 ◽  
Vol 701 ◽  
pp. 159-163 ◽  
Author(s):  
Sheen Jeff Teh ◽  
Yew Keong Sin ◽  
Kah Yoong Chan ◽  
Nisha Kumari Devaraj
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Spin Coating ◽  
Annealing Temperature ◽  
Low Cost ◽  
Sol Gel ◽  
Structural And Optical Properties ◽  
Post Annealing ◽  
Wide Range ◽  
Post Annealing Temperature

Zinc oxide (ZnO) colloid has drawn significant attention recently due to its wide range of potential applications such as photonic crystals, solar cells, sensors, and other optical devices. In this work, low cost sol-gel spin coating technique was employed to synthesis ZnO colloid. The influences of stirring speed and post annealing temperature on the properties of ZnO colloid was investigated. The structural and optical properties of ZnO colloid was characterized using field-emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-Vis) spectrophotometer, respectively. Subsequently, Tauc method was used to estimate the optical band gap of the ZnO colloid based on the optical transmittance data. The effects of the stirring speed and post annealing temperature on the structural and optical properties of ZnO colloid are revealed and discussed in this paper. It was found that ZnO colloid prepared by the stirring speed of 500rpm and 400°C post annealing temperature demonstrates the best dispersity quality of colloid system.

scholarly journals A Novel Top-Down Fabrication Process for Vertically-Stacked Silicon-Nanowire Array

2020 ◽  
Vol 10 (3) ◽  
pp. 1146 ◽  
Author(s):  
Kangil Kim ◽  
Jae Keun Lee ◽  
Seung Ju Han ◽  
Sangmin Lee
Keyword(s):  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Nanowire Array ◽  
Nanowire Arrays ◽  
Fabrication Method ◽  
Top Down ◽  
Silicon Nanowire Arrays ◽  
Sensing Applications ◽  
Silicon Nanowire Array ◽  
Cross Sectional Dimension

Silicon nanowires are widely used for sensing applications due to their outstanding mechanical, electrical, and optical properties. However, one of the major challenges involves introducing silicon-nanowire arrays to a specific layout location with reproducible and controllable dimensions. Indeed, for integration with microscale structures and circuits, a monolithic wafer-level process based on a top-down silicon-nanowire array fabrication method is essential. For sensors in various electromechanical and photoelectric applications, the need for silicon nanowires (as a functional building block) is increasing, and thus monolithic integration is highly required. In this paper, a novel top-down method for fabricating vertically-stacked silicon-nanowire arrays is presented. This method enables the fabrication of lateral silicon-nanowire arrays in a vertical direction, as well as the fabrication of an increased number of silicon nanowires on a finite dimension. The proposed fabrication method uses a number of processes: photolithography, deep reactive-ion etching, and wet oxidation. In applying the proposed method, a vertically-aligned silicon-nanowire array, in which a single layer consists of three vertical layers with 20 silicon nanowires, is fabricated and analyzed. The diamond-shaped cross-sectional dimension of a single silicon nanowire is approximately 300 nm in width and 20 μm in length. The developed method is expected to result in highly-sensitive, reproducible, and low-cost silicon-nanowire sensors for various biomedical applications.

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