Q. Humayun

Area-selective ZnO thin film deposition on variable microgap electrodes and their impact on UV sensing

ZnO thin films were deposited on patterned gold electrodes using the sol-gel spin coating technique. Conventional photolithography process was used to obtain the variable microgaps of 30 and 43 µm in butterfly topology by using zero-gap chrome mask. The structural, morphological, and electrical properties of the deposited thin films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Keithley SourceMeter, respectively. The current-voltage (I-V) characterization was performed to investigate the effect of UV light on the fabricated devices. The ZnO fabricated sensors showed a photo to dark current (Iph/Id) ratios of 6.26 for 30 µm and 5.28 for 43µm gap electrodes spacing, respectively. Dynamic responses of both fabricated sensors were observed till 1V with good reproducibility. At the applied voltage of 1V, the response time was observed to be 4.817s and 3.704 s while the recovery time was observed to be 0.3738 s and 0.2891 s for 30 and 43 µmgaps, respectively. The signal detection at low operating voltages suggested that the fabricated sensors could be used for miniaturized devices with low power consumption.

Structural, optical, electrical, and photoresponse properties of postannealed Sn-doped ZnO nanorods

Tin (Sn) doped ZnO nanorods were synthesized on glass substrate using a sol-gel method. The synthesized nanorods were postannealed at 150, 350, and 500°C. The surface morphologies of Sn-doped ZnO nanorods at different postannealing temperatures were studied using scanning electron microscope (SEM). XRD results show that as the postannealing temperature increased from 150°C to 500°C, the c-axis orientation becomes stronger. Refractive indices and dielectric constants were calculated on the basis of different relationships by utilizing bandgap values. These bandgap values were obtained in terms of optical absorption by using a UV-Visible spectrophotometer. The enhancing effects of annealing temperatures on electrical properties were observed in terms of current-to-voltage measurements. Resistivity decreases as postannealing temperature increases from 150°C to 500°C. Annealed samples were evaluated for UV-sensing application. The samples exhibit a responsivity of 1.7A/W.

Structure Characterization of Low Cost Fabricated Soft Material Built Microchannel

To perform the entire laboratory activities on a centimeter limit scale electronic chip, the most important aspect is to fabricate a device which persist sensitive and selective for the delivery of fluids flow and have the ability to execute a fast mixing of distinctive chemicals and bio samples. To resolve this issues the current paper is one of the good struggle, therefore the objective was arranged in according to the scope of research such as; to design and fabricate a polydimethylsiloxane (PDMS) material made, micro channel and its structure characterization for the investigation of internal subterranean area. By using an AutoCAD software the channel was first designed, however for the fabrication process the design was transferred to mask. Starting from SU-8 resist the pattern was transferred, and then by using the polydimethylsiloxane (PDMS) the mold was fabricated by adopting a low cost photolithography technique. Finally by employing Hawk 3 D surface nanoprofiler the structure was characterized. In our forthcoming research the device will be tested for real biological samples using a simple hand-operated inoculation technique.

Fabrication and characterization of a single-bridge nanorod between microgap electrodes

Purpose – The purpose of this study was to investigate the performance of a single-bridge ZnO nanorod as a photodetector. Design/methodology/approach – The fabrication of the design sensor with ∼6-μm gap Schottky contacts and bridging of the ZnO nanorod were based on conventional photolithography and wet-etching technique. Prior to bridging, the ZnO nanorods were grown by the hydrothermal process. The 0.35 M seed solution was prepared by dissolving zinc acetate dihydrate in 2-methoxyethanol, and monoethanolamine, which acts as a stabilizer, was added drop-wise. Before starting the solution deposition, and oxide, titanium (Ti) and gold (Au) layer deposition, p-type (100) silicon substrate was cleaned with Radio Corporation of America (RCA1) and RCA2, followed by dipping in diluted hydrofluoric acid. The aged solution was dropped onto the surface of the Au microgap structure, using a spin coater at a spinning speed of 3,000 rpm for 45 seconds, and then dried at 300°C for 15 minutes, followed by annealing at...

Micro-Gap Electrodes Fabrication by Low Cost Conventional Photo Lithography Technique and Surface Characterization by Nanoprofiler

The fabrication of sensitive and selective nanodevices is one of the important challenges for future detection of low concentration single bio molecule. The current research article is one of the attempts to achieve such sensitive and selective micro-gap electrodes by simple, low cost controllable process. Therefore high sensitive chrome mask was designed for micro-gap design transformation to wafer samples. At first the positive photoresist namely PR-1 2000A was spin coated on the samples wafer at different rotation speed. Then by implementation of low cost conventional photolithography technique an initial structure of micro-gap was patterned on wafer sample. Finally by using surface Nanoprofiler the thickness of resist coated wafer samples were investigated. The obtained results show that the thickness of the resist is directly related with spin coating speed of spin coater.

Characterization of Micro-Gap Electrodes Initial Pattern on Resist by Employing High Sensitive and Selective Chrome Mask

The detection of most serious diseases at early stages is one of the challenging tasks for researchers of nanotechnology. Therefore the current research article is one of the attempts to fabricate highly sensitive and selective micro-gap electrodes at initial level; such micro-gap electrodes will be used in future for inserting biomolecule in between the gap spacing. To transfer the micro-gap design pattern to sample wafer accurately and preciously, micro-gap was initially designed by using AutoCAD software and the design was finally transferred to high sensitive and selective chrome mask. The article demonstrates experimentally an initial strategy for fabrication of micro-gap electrodes at resisting using conventional photolithography technique coupled with the wet etching process. The structure morphology was characterized using high power and scanning electron microscope namely (HPM and SEM).