Browsing by Author "Soppera, Olivier"

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A low-cost miniaturized colorimetric sensor with vertically-stacked semi-transparent finger-type organic photo detector for formaldehyde sensing
(2019-10-01)
Lin, Ching-Fu
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Zan, Hsiao-Wen
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Lu, Chia-Jung
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Meng, Hsin-Fei
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Soppera, Olivier
We proposed a sensitive colorimetric sensing system using a paper-like sensing layer on top of a vertically stacked finger-type organic photodetector (OPD) and commercial light-emitting diode (LED). The stacked OPD/LED device was small, with an area of 0.8 cm x 0.5 cm that was even smaller than a coin. Using commercial colorimetric formaldehyde (HCHO) sensing molecules to form the sensing layer, the stacked detecting system successfully detected HCHO of concentrations ranging from 40 to 1000 ppb within 20 min. Critical parameters affecting the sensitivity were investigated. The final system exhibited a stable calibration curve over 60 days. The long lifetime was attributed to using 2,6-Bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo [1,2-b:4,5-b']dithiophene (PBDTTT-C-T): phenyl-C71-butyric acid methyl ester (PC71 BM) to serve as a blended system and using the current variation ratio to represent the sensing response.
A Versatile Method to Enhance the Operational Current of Air-Stable Organic Gas Sensor for Monitoring of Breath Ammonia in Hemodialysis Patients
(2019-04-01)
Yu, Shang-Yu
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Tung, Tin-Wei
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Yang, Hong-Yu
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Chen, Guan-Yu
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Shih, Che-Chi
Point-of-care (POC) application for monitoring of breath ammonia (BA) in hemodialysis (HD) patients has emerged as a promising noninvasive health monitoring approach. In this context, many organic gas sensors have been reported for BA detection. However, one of the major challenges for its integration with affordable household POC application is to achieve stable performance for accuracy and high operational current at low voltage for low-cost read-out circuitry. Herein, we exploited the stability of the Donor Acceptor polymer on the cylindrical nanopore structure to realize the sensors with a high sensitivity and stability. Then, we proposed a double active layer (DL) strategy that exploits an ultrathin layer of Poly(3-hexylthiophene-2,5-diyl) (P3HT) to serve as a work function buffer to enhance the operational current. The DL sensor exhibits a sustainable operational current of microampere level and a stable sensing response even with the presence of P3HT layer. This effect is carefully examined with different aspects, including vertical composition profile of DL configuration, lifetime testing on different sensing layer, morphological analysis, and the versatility of the DL strategy. Finally, we utilize the DL sensor to conduct a tracing of BA concentration in two HD patients before and after HD, and correlate it with the blood urea nitrogen (BUN) levels. A good correlation coefficient of 0.96 is achieved. Moreover, the feasibility of DL sensor integrated into a low-cost circuitry was also verified. The results demonstrate the potential of this DL strategy to be used to integrate organic sensor for affordable household POC devices.
Achieving saturation in vertical organic transistors for organic light-emitting diode driving by nanorod channel geometric control
(2013-04-22)
Li, Chang-Hung
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Stehlin, Fabrice
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Wang, Kai-Ruei
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Lin, Yu-Hsin
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Wieder, Fernand
When conventional field-effect transistors with short channel length suffer from non-saturated output characteristics, this work proposed a vertical channel transistor to operate like a solid-state vacuum tube and exhibit good saturated curves. We utilized deep ultra-violet interference lithography to produce ordered grid-like metal to control the potential profile in vertical channel. We compared experimental and simulated characteristics to investigate the keys to achieve saturation. Finally, with an optimized design, a vertical organic transistor is used to drive a solution-processed white-light organic light-emitting diode to perform a luminescence control (0-260 cd/m(2)) with a 3.3-V base potential swing. (C) 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4802999]
Chemical and structural investigation of zinc-oxo cluster photoresists for DUV lithography
(2017-03-14)
Yeh, Chun-Cheng
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Liu, Hung-Chuan
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Heni, Wajdi
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Berling, Dominique
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Zan, Hsiao-Wen
Metal oxo cluster photoresists have drawn a lot of attention in recent years due to their interesting properties combining the advantages of both inorganic and organic features. Their organic functionalities offer the possibility of patterning them by photon or electron beam lithography into metal oxide micro or nanostructures. Thanks to the inorganic metal oxide frameworks, these patterns show higher etch resistance and refractive index in the visible light range than neat organic patterns. Moreover, the nanosize of the photoresist building blocks makes them suitable for high resolution lithography. To have an in-depth understanding of the effect of physicochemical parameters on the size, shape and physical properties of photo-patterned structures, a detailed investigation was carried out on a zinc-oxo cluster photoresist combined with deep ultraviolet (DUV) lithography. The results show the impact of both DUV irradiation and thermal treatment on material patterning. The impact of crystallization is particularly discussed since it has a strong influence on the shape of patterns.
Controllable Formation of Zinc Oxide Micro- and Nanostructures via DUV Direct Patterning
(2016-10-06)
Yeh, Chun-Cheng
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Liu, Hung-Chuan
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Chuang, Ming-Yen
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Denzer, Joseph
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Berling, Dominique
Various kinds of zinc oxide (ZnO) nanostructures, such as ZnO nanowires, ZnO nanobelts, ZnO nanosheets, and ZnO nanorods are promising building blocks for nanoscale systems. However, to precisely control the size, shape, and to make a controlled assembly of synthesized ZnO nanostructures are major difficulties in the development of bottom-up devices. To overcome the challenge regarding reproducibility and positioning, a new method is proposed, deep ultra-violet (DUV) direct photo-patterning, to create ZnO micro- and nanostructures. A sol-gel formulation sensitive to DUV light and based on zinc methacrylate precursor is developed, and the photoreactions of zinc methacrylate under DUV light are carefully investigated by in situ spectroscopic ellipsometry, in situ FTIR, and XPS analysis. Then, the sol-gel solution is used as a negative tone resist in DUV lithography to evaluate its performance in producing high-resolution patterns. The results indicate that small patterns from micro-to nanoscale can be obtained in a simple and direct way.
Deep ultraviolet laser direct write for patterning sol-gel InGaZnO semiconducting micro/nanowires and improving field-effect mobility
(2015-05-27)
Lin, Hung-Cheng
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Stehlin, Fabrice
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Soppera, Olivier
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Zan, Hsiao-Wen
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Li, Chang-Hung
Deep-UV (DUV) laser was used to directly write indium-gallium-zinc-oxide (IGZO) precursor solution and form micro and nanoscale patterns. The directional DUV laser beam avoids the substrate heating and suppresses the diffraction effect. A IGZO precursor solution was also developed to fulfill the requirements for direct photopatterning and for achieving semi-conducting properties with thermal annealing at moderate temperature. The DUV-induced crosslinking of the starting material allows direct write of semi-conducting channels in thin-film transistors but also it improves the field-effect mobility and surface roughness. Material analysis has been carried out by XPS, FTIR, spectroscopic ellipsometry and AFM and the effect of DUV on the final material structure is discussed. The DUV irradiation step results in photolysis and a partial condensation of the inorganic network that freezes the sol-gel layer in a homogeneous distribution, lowering possibilities of thermally induced reorganization at the atomic scale. Laser irradiation allows high-resolution photopatterning and high-enough field-effect mobility, which enables the easy fabrication of oxide nanowires for applications in solar cell, display, flexible electronics, and biomedical sensors.
Direct Laser Writing of Crystallized TiO2 and TiO2/Carbon Microstructures with Tunable Conductive Properties
(2018-12-01)
Yu, Shang-Yu
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Schrodj, Gautier
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Mougin, Karine
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Dentzer, Joseph
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Malval, Jean-Pierre
Metal oxides are an important class of materials for optoelectronic applications. In this context, developing simple and versatile processes for integrating these materials at the microscale and nanoscale has become increasingly important. One of the major remaining challenges is to control the microstructuration and electro-optical properties in a single step. It is shown here that near-infrared femtosecond laser irradiation can be successfully used to prepare amorphous or crystallized TiO2 microstructures in a single step using a direct laser writing (DLW) approach from a TiO2 precursor thin film doped with a suitable dye. When laser writing is conducted under a nitrogen atmosphere, simultaneous to the crosslinking of the Ti-oxide precursor, the graphitization of the organic species embedded in the initial film is observed. In this case, a carbon network is generated within the TiO2 matrix, which significantly increases the conductivity. Moreover, the TiO2/C nanocomposite exhibits piezoresistive behavior that is used in a pressure sensor device. Using this route, it is possible to use DLW to fabricate microsized pressure sensors.
Laser Polymer Tattooing: A Versatile Method for Permanent Marking on Polymer Surfaces
(2019-12-01)
Chang, Po-Yi
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Bruntz, Adele
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Vidal, Loic
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Vetter, Pierre-Alain
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Roudot, Patrick
A versatile and efficient method for the permanent marking of polymer surfaces that combines inkjet deposition and near-infrared (NIR) laser curing is investigated. The NIR laser treatment forces the ink particles to migrate into the upper layers of the polymer. This results in the fixation of a permanent grayscale image that can be applied to various polymers, such as polypropylene, which is widely used in industry but still difficult to mark. The physiochemical processes induced by laser curing are investigated by electronic and optical microscopy. The dependence of the thickness of the deposited ink and the laser power on the contrast of marking are also studied. A mechanism implying fast laser-induced melting of the polymer surface followed by displacement of carbon nanoparticles by convection is proposed. Finally, a comparison of the aging properties of samples prepared by this process and standard UV ink is proposed to illustrate the interesting nature of this new polymer marking process. Integrating the ink under the surface of the polymer, as in a skin tattooing procedure, by laser curing is an efficient way to generate permanent images on polymer surfaces.
Low-temperature sol-gel oxide TFT with a fluoropolymer dielectric to enhance the effective mobility at low operation voltage
(2017-06-01)
Yu, Shang-Yu
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Wang, Kuan-Hsun
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Zan, Hsiao-Wen
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Soppera, Olivier
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光電工程學系
In this article, we propose a solution-processed high-performance amorphous indium-zinc oxide (a-IZO) thin-film transistor (TFT) gated with a fluoropolymer dielectric. Compared with a conventional IZO TFT with a silicon nitride dielectric, a fluoropolymer dielectric effectively reduces the operation voltage to less than 3V and greatly increases the effective mobility 40-fold. We suggest that the dipole layer formed at the dielectric surface facilitates electron accumulation and induces the electric double-layer effect. The dipole-induced hysteresis effect is also investigated. (C) 2017 The Japan Society of Applied Physics
Nanoscale Ferromagnetic Cobalt-Doped ZnO Structures Formed by Deep-UV Direct-Patterning
(2017-11-23)
Yeh, Chun-Cheng
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Colis, Silviu
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Fioux, Philippe
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Zan, Hsiao-Wen
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Berling, Dominique
Cobalt (II) acetate is mixed with zinc methacrylate (ZnMAA) to form a photopatternable Co-doped zinc oxide precursor. By using deep-UV (DUV) interference lithography, Co-doped ZnMAA precursor can be patterned as negative tone resist and transformed into ferromagnetic Co:ZnO films after thermal treatment. Moreover, Co:ZnO patterns as small as 300 nm line-width can be easily obtained. To have an in-depth understanding to the effect of DUV-patterning process as well as thermal annealing on Co:ZnO films derived from Co-doped ZnMAA precursor, optical, magnetic, and electrical characterizations are performed on Co:ZnO films prepared in different conditions. For the Co:ZnO film prepared without DUV-patterning, large zero-field-cooling (ZFC)-field-cooling (FC) irreversibility appears in superconducting quantum interference device measurements after vacuum annealing, indicating that Co clusters have formed inside the film. On the other hand, no ZFC-FC bifurcation can be observed for the DUV-patterned Co:ZnO film after the vacuum annealing, suggesting that the uniformity of Co ion distribution inside ZnO lattice is improved by DUV-patterning.
Near-Infrared Laser-Annealed IZO Flexible Device as a Sensitive H2S Sensor at Room Temperature
(2020-06-03)
Chang, Po-Yi
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Lin, Ching-Fu
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Rouphael, Samer El Khoury
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Huang, Ting-Hsuan
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Wu, Chang-Mao
A metal-oxide material (indium zinc oxide [IZO]) device with near-infrared (NIR) laser annealing was demonstrated on both glass and bendable plastic substrates (polycarbonate, polyethylene, and polyethylene terephthalate). After only 60 s, the sheet resistance of IZO films annealed with a laser was comparable to that of thermal-annealed devices at temperatures in the range of 200-300 degrees C (1 h). XPS, ATR, and AFM were used to investigate the changes in the sheet resistance and correlate them to the composition and morphology of the thin film. Finally, the NIR-laser-annealed IZO films were demonstrated to be capable of detecting changes in humidity and serving as a highly sensitive gas sensor of hydrogen sulfide (in ppb concentration), with room-temperature operation on a bendable substrate.
Photo-assisted recovery in ammonia sensor based on organic vertical diode
(2019-04-01)
Lin, Yu-Ting
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Yu, Shang-Yu
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Zan, Hsiao-Wen
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Yeh, Ping-Hung
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Lu, Chia-Jung
In this article, a photo-assisted gas sensor was provided to solve the slow recovering issue of the organic gas sensor. The proposed organic gas sensor can detect ammonia in parts-per-billion regime in 30 s and can be multiple uses, but the long recovery time about 5 min places difficulty to realize rapidly multiple-time sensing. Therefore, we used the photo-absorption ability in the organic semiconductor layer to generate the photocurrent and hence to compensate the current drop due to the ammonia absorption. The recovery time was significantly reduced to be only 1 min. The specific wavelength was also found to match the absorption spectrum in different organic sensing materials. As a comparison, the quartz crystal microbalance (QCM) was used to clarify the gas absorption and desorption mechanism. It is believed that this photo-assisted gas detection could be a general method to solve the slow recovery in organic-based gas sensors.
Simple silver nanowire patterning using a DUV lamp direct write with sol-gel IZO capping
(2017-01-01)
Liu, Hung-Chuan
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Zan, Hsiao-Wen
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Soppera, Olivier
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Zhang, Yi
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Yang, Bo-Ru
Herein, we developed a simple method to pattern a silver nanowire (AgNW) electrode using a DUV lamp to directly write on an indium-zinc-oxide capped AgNW. The patterning was achieved via directly transferring the DUV-write IZO pattern to the AgNW pattern because the IZO film protected the AgNWs from melting during the subsequent thermal annealing step. The patterned AgNW electrodes retained good conducting properties on a flexible polyimide substrate after 1000 bending cycles. This DUV-lamp-write pattern method is promising to form a AgNW pattern on a large area and flexible substrate for sensor or photovoltaic applications.
Solution-Based Micro- and Nanoscale Metal Oxide Structures Formed by Direct Patterning for Electro-Optical Applications
(2018-12-13)
Yeh, Chun-Cheng
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Zan, Hsiao-Wen
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Soppera, Olivier
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光電工程學系
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光電工程研究所
Due to their transparency and tunable electrical, optical, and magnetic properties, metal oxide thin films and structures have many applications in electro-optical devices. In recent years, solution processing combined with direct-patterning techniques such as micro-/nanomolding, inkjet printing, e-jet printing, e-beam writing, and photopatterning has drawn much attention because of the inexpensive and simple fabrication process that avoids using capital-intensive vacuum deposition systems and chemical etching. Furthermore, practical applications of solution direct-patterning techniques with metal oxide structures are demonstrated in thin-film transistors and biochemical sensors on a wide range of substrates. Since direct-patterning techniques enable low-cost fabrication of nanoscale metal oxide structures, these methods are expected to accelerate the development of nanoscale devices and systems based on metal oxide components in important application fields such as flexible electronics, the Internet of Things (IoT), and human health monitoring. Here, a review of the fabrication procedures, advantages, limitations, and applications of the main direct-patterning methods for making metal oxide structures is presented. The goal is to highlight the examples with the most promising perspective from the recent literature.
The zinc-loss effect and mobility enhancement of DUV-patterned sol-gel IGZO thin-film transistors
(2018-03-01)
Wang, Kuan-Hsun
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Zan, Hsiao-Wen
;
Soppera, Olivier
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光電工程學系
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Department of Photonics
We investigate the composition of the DUV-patterned sol-gel indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) and observe a significant zinc loss effect during developing when the DUV exposure is insufficient. The zinc loss, however, is beneficial for increasing the mobility. Reducing zinc to indium composition ratio from 0.5 to 0.02 can effectively increase mobility from 0.27 to 7.30 cm(2) V-1 s (-1) when the gallium to indium ratio is fixed as 0.25 and the post annealing process is fixed as 300 degrees C for 2 h. On the other hand, an IGO TFT fails to deliver a uniform film and a reproducible TFT performance, revealing the critical role of zinc in forming homogeneous IGZO TFTs.