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A capacitive force sensor is one of the electronics components used in several electronic devices and applications. An improvement of sensing characteristics of the sensor, for example sensitivity and response time, becomes an interesting research topic. The alternative approach to enhance the sensitivity and response time of polydimethylsiloxane‐based capacitive force sensors is proposed by introducing poly(3,4‐ethylenedioxythiophene) polystyrene sulphonate, a conductive polymer, into polydimethylsiloxane active layer. Two sensors using different active layers, (i) polydimethylsiloxane (conventional sensor) and (ii) poly(3,4‐ethylenedioxythiophene) polystyrene sulphonate mixed polydimethylsiloxane (modified sensor), were fabricated and characterised to reveal the sensing enhancement. Interestingly, the modified sensor shows the significant increase in the sensitivity from 0.7 to 1.14 kPa–1 (+62.86%) and the shortening response time from 1.55 to 0.43 s (−72.26%) with respect to the conventional sensor. In addition, the deterioration in elastic behaviour and the faster charge–discharge behaviour observed from the poly(3,4‐ethylenedioxythiophene) polystyrene sulphonate mixed polydimethylsiloxane film indicate the better deformation and charge transport than that from polydimethylsiloxane film. Therefore, it can be concluded that the conductive poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate additive plays the role of mechanical and electrical modification of the polydimethylsiloxane active layer leading to the enhancement in sensitivity and response time of the polydimethylsiloxane‐based capacitive force sensor.

The amorphous tantalum oxynitride (TaO x N y ) thin films were prepared on silicon (100) substrates by magnetron sputtering system with different techniques of conventional reactive sputtering and reactive gas-timing (RGT). The films were studied via spectroscopic ellipsometry (SE) measured in the range of 0.75–5.0 eV with 0.025 eV interval at 70° incident angle, and the optical model based on Tauc-Lorentz function was constructed to extract the properties of the films. The SE results indicated that all prepared films were grown homogeneously and show different optical properties upon their deposition conditions and techniques. The optical properties of film prepared by conventional reactive sputtering were close to the tantalum oxide film (TaO). The refractive index and optical band gap (E g ) of RGT samples changed with the oxygen timing and correlated with the change of oxygen and nitrogen concentration of the films. In addition, the morphologies, crystallinities, atomic concentrations and distributions of nitrogen atoms in the films analyzed by field-emission scanning electron microscopy, glazing-incident X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are also discussed.

Organometallic halide perovskite materials with the general formula ABX3 have been recently interested as active layers in perovskite solar cells. It is well known that the O2 is the main problem for fabricated perovskite solar cells. Usually, the perovskite thin film need to be prepared in the N2 atmosphere or in the glove box. In this research, the metal halide perovskite CH3NH3PbI2Cl thin films were successfully deposited using spin-coating technique via a single step solution deposition and CH3NH3Cl as additive in sequential deposition process in the open air. The effect of annealing temperature on the organolead halide perovskite phase formation of CH3NH3PbI2Cl thin film was investigated. The phase formation as well as crystal structure were investigated by X-ray diffractometer, and we found that organolead halide perovskite thin film exhibited a pure phase perovskite without the unwanted phases. The crystallinity of the perovskite thin film was enhanced significantly by increasing the annealing temperature, and a single phase of the perovskite phase was observed by increment of the annealing temperature that is above 100OC. In addition to this, the growth of crystallinity in the halide perovskite thin film was increased with increasing heat treatment temperature. Furthermore, the morphology variation of the thin films were examined by Field Emission Scanning Electron Microscopy.

In this research, antimony doped ZnO (SZO) thin films with various doping content have been grown on a c-Al2O3 substrate by pulsed laser deposition. The effect of the applied electric field on the bandgap of SZO thin films was studied by electroreflectance (ER) spectroscopy using a capacitor-type geometry. Hall effect measurements indicate that the p-type conductivity of SZO is realized for the Sb2O3 weight percentage at 2%. The blue shift of the energy bandgap was observed in thin films after increasing the doping concentration. The Burstein-Moss effect is the crucial mechanism for the blue shift of the SZO bandgap. Furthermore, we found the red shift of bandgap in all samples, which was measured under various electric fields by ER spectroscopy. The changes of the optical transition in the band structure should be the origin of the red shift behaviors of the SZO bandgap under the presence of the electric field. Based on our results, we can design and optimize the bandgap of SZO for optoelectronic devices.

The aim of this research is to introduce the alternative process named “Rapid Convective Deposition” to obtain organic thin film in nanometer scale. There are several advantages of this method, including simply control film thickness via solution concentration and translational speed as well as significantly reduce required material leading to lower manufacturing cost. The specific properties of thin film were characterized by the combinations of microscopic and spectroscopic techniques. To confirm that the convective deposition has a potential to become a candidate method using to prepare thin film, the films prepared by conventional spin coating and alternative convective deposition were compared in term of processing e.g. required solution as well as processing time and film’s properties e.g. thickness, morphology and uniformity of the film. The results indicate that the rapid convective deposition is able to provide similar film’s quality as obtain from spin coating but requires less processing time and required solution to prepare the nanoscale organic thin film.

Electrodes based on low-temperature preparation such as ink jet printing have been famously used in plastic electronic devices. The aim of this work is to investigate the specific properties of composite materials between nanoparticles of indium tin oxide (np-ITO) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as an alternative electrode for plastic electronic devices. The composite materials were prepared as a function of np-ITO concentration varied from 1 to 20 w/v%. The 1x1 cm 2 hybrid electrodes were fabricated by drop casting method on the microscope slide. This method offers many advantages, including simple preparation, low manufacturing cost and short fabricating time. The electrical resistance of the hybrid films was measured using two-probe measurement. Moreover, the surface morphology of the composited film was explored by optical microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results clearly suggest that mixing np-ITO with PEDOT:PSS can significantly improve conductivity of the composited system. Average value of electrical resistance measured from np-ITO, PEDOT:PSS and composite film are 87.58 kΩ, 40.33 kΩ and 393 Ω, respectively. The significant reduction of film resistance can be explained by the conducting paths made up by PEDOT:PSS to connect np-ITO domain.

We investigate charge transport in UV sensing devices based on organic-inorganic semiconductor composites with the metal-semiconductor-metal (MSM) structure. Composite materials of zinc oxide (ZnO) nanoparticles and poly(3-hexylthiophene) (P3HT) were prepared by drop-casting their colloidal mixture in chloroform onto low-cost interdigitated copper electrodes. The current-voltage characteristics of the devices were investigated under both dark and illuminated conditions in the UV–visible range. The highest photoresponse was observed for an optimal P3HT:ZnO ratio of 1:8 w/w in the wavelength range between 310 and 380 nm. The dynamic response was investigated by pulsing a 365 nm UV light with a long period to reveal the response time of 4 s and the recovery time of less than 1 s. The photoresponse of the materials was also investigated for a shorter period of UV pulsing, using a rotating chopper. The response time and recovery time for the short UV pulse were found to be approximately 20 m and 25 m, respectively. The dual response times should stem from the presence of two types of semiconductor materials, namely ZnO with a high electron mobility and P3HT with a moderate hole mobility. To probe the charge generation and transport mechanisms, we further investigate the photoresponse using UV pulsing under background white light of different intensities, and vice versa. The background white light was found to deteriorate the UV photoresponse of the materials. On the other hand, the background UV illumination produced an anomalous photoresponse pattern with the white light pulsing. Understanding the charge transport mechanisms for composite materials is highly important for future applications in low-cost UV sensors and tunable optoelectronic devices.

In this work, sensitivity and response times of PDMS-based capacitive force sensors are enhanced via the modifications of the PDMS layer. Two modifying approaches are proposed; (i) change PDMS’s (elastomer:curing agent) ratio and (ii) adding conductive polymer PEDOT:PSS into the PDMS layer. The change of PDMS (elastomer:curing agent) ratio from (10:1) to (30:1) increases the sensitivity from 0.4 ± 0.08 to 0.72 ± 0.23 kPa−1 (+80%) but it does not significantly affect the response/recovery times. In addition, by adding 1% wt. of PEDOT:PSS to PDMS (30:1), the further increment of sensitivity from 0.72 ± 0.23 to 1.44 ± 0.17 kPa−1 (+100%) and the shorter response time from 1.59 ± 0.02 to 0.45 ± 0.03 s (−72%) are observed. The mechanical and electrical studies reveal that the change of PDMS (elastomer:curing agent) ratio and the adding of PEDOT:PSS to PDMS layer result in the modification of PDMS’s deformability and the increase of charge transportation, leading to the enhancement of sensing characteristics of the sensors.

The aim of this research is to control specific properties of nickel-phthalocyanine (NiPc) thin film by doping with tin (Sn). The hybrid thin films, Sn-doped NiPc, were fabricated by thermal co-evaporation as a function of Sn concentration. The quantity of Sn in NiPc matrix was controlled via the different deposition rate between Sn and NiPc. The specific properties of the hybrid films, e.g. morphology, optical absorption, chemical bonding as well as electrical characteristics of the devices used such hybrid material as an active layer were characterized by combinations of microscopic and spectroscopic techniques. The experimental results evidently present the modification of thin film properties by adding Sn into NiPc matrix, i.e. the change of morphology from granules to fibers, the increase of beta-phase formation in the films as well as the enhancement of electrical properties resulting from the increase of both charge carrier mobility and carrier concentration in the hybrid material. Moreover, the internal formation of the Sn-doped NiPc reveals that Sn dopants are embedded in the NiPc matrix as Sn metal clusters coated with derivative metal oxide of Sn (SnOx). This research demonstrates that the doping metal-phthalocyanine with metal is an alternative approach to control the specific properties that possibly suit for organic electronic applications.

In this paper, we demonstrate a novel technique, as called reactive gas-timing (RGT) RF magnetron sputtering, to control and design an optical band engineering of TaON thin films without an external heating substrate temperature and post annealing treatment process. The influence of the oxygen intervals ranged from 5 to 60 s on deposition rate, chemical composition and optical properties of TaON thin films were investigated. The chemical composition was characterized by auger electron spectroscopy (AES). The optical properties were determined by UV–Vis spectrophotometer and spectroscopic ellipsometry. The nitrogen atomic concentration of the TaON thin films deposited by RGT decreased when the oxygen gas-timing intervals increased. In addition, the RGT sputtered TaON films could be demonstrated band gaps engineering from 1.90 to 2.15 eV.

This work presents the development of nitrate sensor based on Ion Sensitive Field Effect Transistor (ISFET) technology to achieve longer device's lifetime. This lifetime depended on the adhesion of PVC ion-selective membrane on the Si3N4 sensing membrane of ISFET. The adhesion level directly affected the leaching of plasticizer. Such improvement utilized surface modification techniques by immersing the sensing membrane in the solution of 5% 3-mercaptopropyl-trimethoxysilane (MPTMS)/methanol. The modified surface was detected through the change of hydrophobicity and thickness of MPTMS using the contact angle measurement and ellipsometry techniques. The appropriate time for immersion was 18 h. The modified surface achieved the optimal hydrophobicity with contact angle of 100.32°. The presence of MPTMS film was confirmed by detecting the thiol-group using Fourier Transform Infrared (FTIR) spectrophotometry and Auger Electron Spectroscopy (AES). The PVC ion-selective membrane was then immobilized on the surface to create nitrate sensors with the following characteristics. The Nitrate-Nitrogen detection limit = 2.44 ppm with linear range from 5 to 60 ppm at sensitivity of 56 mV/dec. (R2 = 1). The response time was 90 s. Finally, this nitrate sensor could extend the total utilization lifetime from 8 to 17 weeks.

A novel molecularly imprinted electrochemical sensor based on ISFET device has been developed for urea detection sensor. The molecularly imprinted polymers (MIPs) were prepared by photopolymerization on the surface of ISFET device using PMMA and urea as the functional polymer and molecular template, respectively. The fabricated sensors were characterized by potentiometry and UV-Vis spectroscopy. The preparation conditions were optimized for performance of the sensors, i.e. drop-cast volume and incubation time. The MIP modified ISFET sensors has linear range response from 1.0 × 10− 4 to 1.0 × 10− 1 M with the limit of detection of 1.0 × 10− 4 M (S/N = 3). The MIP modified ISFET sensors also exhibit excellent reproducibility, repeatability and stability, as well as high selectivity to urea.

Hybrid magnetic nanoparticles based on poly(methylmethacrylate) (PMMA) and super-paramagnetic iron oxide nanopaticles (SPIONs) with selective surface modification has been developed for heavy metal removal by applying external magnetic fields. The nanoparticles were prepared by the emulsion polymerization technique in an aqueous suspension of SPIONs. The hydrolysis of carboxyl functional group was then applied for grafting polyethylene glycol bis(amine)(PEG-bis(amine)) onto the PMMA-coated SPIONs. The morphology, the chemical structure and the magnetic properties of the grafted nanoparticles were investigated. The efficiency of the hybrid nanoparticles for heavy metal removal were conducted on Pb(II), Hg(II), Cu(II) and Co(II) in aqueous solutions.The metal concentration in the solutions after separation by the hybrid nanoparticles was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results show the heavy metal uptake ratios of 0.08, 0.04, 0.03, and 0.01 mM per gramme of the grafted SPIONs for Pb(II), Hg(II), Cu(II), and Co(II), respectively. A competitive removal of Cu(II), Pb(II), Co(II) and Hg(II) ions in mixed metal salt solutions has also been studied.The heavy metal removal efficiency of the hybrid nanoparitcles was found to depend on the cation radius, in accordance with capture of metal ions by the amine group.

The aim of this work is to investigate specific properties of tin-doped magnesium phthalocyanine (Sn-doped MgPc) thin films grown by thermal co-evaporation. Morphological, optical and chemical properties of the doped-films were characterized by atomic force microscopy (AFM), UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS). Furthermore, electrical properties of ITO/Sn-doped-MgPc/Al devices such as carrier mobility and carrier concentration were extracted from current-voltage and capacitance-voltage measurements. Morphology of the doped films shows strong dependence on the existence of Sn in the doped films as clearly observed by changing of features of the film surface e.g. surface grain size and roughness. Optical absorption spectra of all conditions provide regular three dominant beta-phase peaks at 352, 640 and 691 nm corresponding to absorption from B-band and Q-band, respectively. The electrical properties obtained from ITO/Sn-doped MgPc/Al device suggest that the enhancement of the current flow in the doped device is a result from the increase of both carrier mobility and carrier concentration. Moreover, photoelectron analysis reveals two formations of Sn dopant in MgPc those are tin metal and derivative of tin oxide.

The objective of this work is to investigate the optical and electrical properties of bismuth-doped nickel-phthalocyanine thin films (Bi-doped NiPc). The doped films were prepared by thermal co-evaporation as a function of Bi concentration. The amount of Bi in NiPc was controlled via different deposition rates between metal dopant and organic host. The optical properties of the hybrid films were characterized by spectroscopic techniques. Furthermore, the electrical properties e.g. charge carrier concentration and carrier mobility of Al/Bi-doped-NiPc/ITO devices were characterized by current-voltage and capacitance-voltage measurements. The results of optical properties suggest that the crystalline packing of NiPc molecules in all preparation conditions is a combination of α-phase (majority) and β-phase (minority). However, the evolution of β-phase NiPc is observed with the increase of metal doping concentration. Raman spectroscopic results reveal that there is no chemical bond taken place between Bi and NiPc. In addition, with increasing dopant concentration, electrical properties present the enhancement of conducting current of hybrid devices as result from the increment of both charge carrier concentration and charge carrier mobility.

Here we demonstrate a special technique to control a texture orientation of silver (Ag) thin films using gas-timing (GT) rf magnetron sputtering. By utilizing a GT technique, a dense structure and a high ratio of (111)/(200) of Ag films could be obtained without applying additional energy sources. We found that the GT technique not only provides the ability to adjust the number of sputter species from the target, but also generates the self-energy assisted deposition which related to the atomic peening effect. Furthermore, we found that a high (111)/(200) ratio of Ag films strongly affects the SERS activity of the Ag films due to a hot spot effect. Our results highlight that the texture engineering of metal thin films could be accomplished by using a GT technique.

Herein, we demonstrate a powerful technique, known as reactive gas-timing (RGT) rf magnetron sputtering, to fabricate high quality Zn3N2 thin films at room temperature without applying any additional energy sources. A single phase of Zn3N2 film formation can only be obtained when a reactive pulse-gas of N2 is utilized. We find that selecting a small atomic mass of sputtered reactive gas coupled with the pulse-gas technique is very crucial to adjust the number of sputtered atoms obtained from the target and enrich the forming energy of the sputtered Zn3N2 films during the deposition process. Our results highlight that the RGT technique is a promising method to fabricate high quality sputtered compound thin films that can be applied in flexible devices. A simplified model of the materials system at the surface region of the de-nitride Zn3N2 during ion bombardment is also presented.

Tin-doped nickel phthalocyanine thin films (Sn-doped NiPc) were deposited by thermal co-evaporation method. Doping concentration of tin in NiPc was controlled via different deposition rates between metal dopent and host organic material. Properties of the thin films doped by tin in the range of 3 to 15% were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS). Furthermore, electrical properties of Al/Sn-doped-NiPc/ITO devices i.e. charge carrier concentration and carrier mobility were characterized by current-voltage and capacitance-voltage measurements. Microscopic results show clear evidence of the morphological transition from granular structure in undoped-film to rod-liked structure in the films doped more than 5%. Moreover, surface grain size exhibits the tendency to decrease with the increase of doping concentration. Optical properties reveal that the packing of NiPc molecules in all doping conditions is the combination of α-phase (majority) and β-phase (minority). However, evolution of β-phase NiPc is observed with the increase of doping concentration. Photoelectron analyses indicate shift of binding energy in both Ni2p and Sn3d levels corresponding to charge transfer between nickel-core and tin dopant. In addition, the electrical properties show the enhancement of the film’s conductivity due to the increase of charge carrier concentration with the higher Sn-doping level.

A micro-volume electronic tongue based on cyclic voltammetry with two sensing electrodes (gold and carbon) and a platinum pseudo-reference electrode is proposed to classify fertilizers and monitor fertilizer uptakes. The electronic tongue has been employed to classify three different types of commercial fertilizers and their mixture. The nutrient uptake of Dracaena Sanderiana (D. Sanderiana) planted in crystal soil with the mixture fertilizer was monitored by sampling the fertilizer solutions with the electronic tongue over a period of one week. The contents of macronutrients in the solutions were also analyzed by the standard spectroscopic techniques for comparison. A good agreement is obtained between the relative uptakes of phosphate and potassium from the electronic tongue analysis and those from the standard analytical techniques.

Bismuth-doped copper phthalocyanine (Bi-doped CuPc) thin films were grown by organic-source thermal co-evaporation under five different deposition rates. Morphological, optical and chemical properties of the doped-films were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS). Furthermore, electrical properties of ITO/Bi-doped-CuPc/Al devices i.e. carrier mobility and carrier concentration were characterized by current-voltage and capacitance-voltage measurements. Morphology of the doped films shows strong dependence on preparation conditions, as clearly observed by features of film surface i.e surface grain size and roughness. Optical absorption spectra of all doping conditions provide regular three dominant α-phase peaks at 339, 620 and 695 nm corresponding to absorption from B-band and Q-band, respectively. Electrical properties exhibit the enhancement of the film conductivity due to increase of both carrier mobility and carrier concentration with higher Bi-doping level. Moreover, photoelectron analysis reveals chemical information of the metal dopant in the host material.

This research is related to growth and characterizations of indium-doped pentacene thin films as a novel hybrid material. Doped films were prepared by thermal co-evaporation under high vacuum. The doping concentration was varied from 0% to 50% by controlling the different deposition rate between these two materials while the total thickness was fixed at 100 nm. The hybrid thin films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-Visible spectroscopy to reveal the physical and optical properties. Moreover, the electrical properties of ITO/indium-doped-pentacene/Al devices i.e. charge mobility and carrier concentration were determined by considering the relationship between current-voltage and capacitance-voltage. AFM results identify that doping of indium into pentacene has an effect on surface properties of doped films i.e. the increase of surface grain size. XRD results indicate that doping of metal into pentacene has an effect on preferential orientation of pentacene’s crystalline domains. UV-Vis spectroscopy results show evolution of absorbance at photon energy higher than 2.7 eV corresponding to absorption from oxide of indium formed in the films. Electrical measurements exhibit higher conductivity in doped films resulting from increment of both charge carrier mobility and carrier concentration. Furthermore, chemical interactions taken place inside the doped films were investigated by x-ray photoelectron spectroscopy (XPS) in order to complete the remaining questions i.e. how do indium atoms interact with the neighbor molecules?, what is the origin of the absorption at E > 2.7 eV? Further results and discussions will be presented in the publication.

Silicon nitride is a promising alternative to carbon based materials for protective coatings, owing to its compatibility with existing silicon-based microfabrication. The complexity of the fabrication processes and contaminations hamper fine-tuning to obtain desirable coating properties. We have explored the reactive gas-timing rf plasma sputtering technique for silicon nitride thin film deposition as an alternative method to fine-tune the film properties. The gas-timing technique controls the on-off sequence of the sputtering gas (Ar) and the reactive gas (N2) during deposition. We focus this investigation to the effect of the Ar:N2 gas timing ratio (10:0, 10:1, 10:3, 10:5, 10:7 and 10:10) on the composition, the morphology, the corrosion resistance, and the hardness properties of the films, in comparison to the films deposited by conventional reactive sputtering with Ar-N2 gas mixture. These deposited silicon nitride films were characterized by Auger electron spectroscopy, Raman spectroscopy, and atomic force microscopy. The chemical resistance was measured by the electrochemical corrosion test in sulfuric acid, while the hardness properties were obtained by nanoindentation. The results reveal that although the nitrogen content in the films increases only slightly when the N2 timing is prolonged, the corrosive current of the films decreases abruptly. A thin passivating oxidized layer is found to play a major role in the corrosion resistance. In contrast, the hardness properties exhibit a uniform variation with the N2 timing. The gas-timing sequence may induce morphological changes the underlying silicon nitride films. The highest hardness obtained by the gas-timing technique almost doubles that produced by the conventional mixed gas sputtering. Thus the reactive gas-timing technique suggests a new route to selectively control the properties of silicon nitride films with minor modification to existing microfabrication processes. Copyright © 2015 VBRI Press.

A solid state thermal switching device can regulate carrier transport by triggering of its critical transition temperature (T c) by applied external thermal energy. Continuous control of the T c of the thermal switch by the metal–insulator transition (MIT) phenomenon makes such devices widely usable. In this research, tunable thermal switching devices were fabricated, and characterization of the MIT in VO2 thin film phase transition material was studied as a function of temperature and the external applied electric field. We observed reversible abrupt changes of the electrical resistivity by approximately three orders of magnitude at T c = 62.3 °C for VO2 thin film on a SiO2/Si substrate. The MIT induced by the external electric field successfully controlled the T c of the thermal switch between 60 °C and 47 °C (as a linear relationship). We found that the Joule heating effect, rather than electric field breakdown, was a dominant mechanism due to the configuration of the device.

Here, the dependence of growth time on the growth behavior, morphology and photoelectrochemical (PEC) properties of ZnOnanorods (ZnO-NRs) as a photoanode are demonstrated. Vertical-aligned ZnO-NRs with [Formula: see text]-axis perpendicular to substrate were accomplished via seed-assisted hydrothermal technique at the growth time varying between 0.5 and 24[Formula: see text]h. Growth behaviors of ZnO-NRs can be described into three regimes, which consist of the nucleation stage, ZnO-NRs growth and saturation growth, respectively. ZnO nanoparticles (NPs) corresponding to the nucleation site occur at the growth time below 1[Formula: see text]h. Afterward, the growth regime of ZnO-NRs, which originated from the competition between the vertical and the lateral growth, is clearly observed, and leads to increase in length and diameter. The whole growth of ZnO-NRs is terminated after 16[Formula: see text]h, attributed to low amount of Zn[Formula: see text] and OH− supplied from growth solution. PEC measurement reveals the fast solar response and high photostability of ZnO-NRs. Additionally, the photoconversion efficiency ([Formula: see text] improves with the growth time of 4[Formula: see text]h and degrades for longer time due to the change of total surface area. The maximum [Formula: see text] of 0.13% at 0.63[Formula: see text][Formula: see text] is obtained for the growth time of 4[Formula: see text]h. Our results highlight that the growth time plays a crucial role in controlling growth behavior and the total surface area directly related with the PEC properties of ZnO-NRs.

Solid state pH-sensor device with high efficiency has successfully prepared by using TiN thin film as sensing membrane of extended gate field effect transistor (EG-FET) device. This research has described the physical properties and sensing characteristics of TiN membrane thin film which deposited on SiO2/Si substrate through reactive D.C. magnetron sputtering system. Thenanocrytal-TiNwith anatasestructure depended on substrate heating conditions was revealed from glancing angle x-ray diffraction. The IDS-VGS measurement in the standard buffer solutions showed that the sensitivity of fabricated TiN-EGFET pH deviceis 59.82mV/pH.

Sn doped ZnPc films were deposited on intrinsic Si and glass substrates by organic source thermal co-evaporation technique with different deposition rates. Optical properties and electronic structure were characterized by UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) respectively. The UV-Vis results showed that phase transition of ZnPc from α-phase to β-phase occurred when Sn:ZnPc deposition rate is 0.3:0.7 or higher. XPS results indicated that the outer s electron of Sn atom is transferred to the ZnPc. Broadening of the C 1s spectra is observed with the increasing of Sn deposition rate. This broadening corresponds to the change of molecular environment surrounding carbon atoms in the Sn-doped ZnPc films.

A blend of molecular acceptor and molecular donor made of Copper Phthalocyanine (CuPc) and Indium in various ratios were evaporated in high vacuum on to intrinsic silicon substrates by using vacuum thermal co-evaporation technique. Electronic properties of In-doped CuPc thin films have been examined by X-ray photoelectron spectroscopy (XPS). The results obtained by XPS suggests that In-doped CuPc is a hole transport material.

We investigate the increase of C-H vibration in benzene rings of pentacene molecule upon doping with indium by the X-ray photoelectron spectroscopy (XPS) characterization technique. The risen of C-H vibration spectral component is employed to demonstrate the charge transfer between In dopant atoms and C atoms in benzene rings of pentacene molecule. This experiment can be used to explain the same mechanism of charge transfer between In dopant atoms and C atoms in In-doped nickel-phthalocyanine(NiPc).

Tantalum oxide (Ta2O5) thin films, 100 nm thick were deposited by D.C. reactive magnetron sputtering system at different operated pressure on unheated p-type silicon (100) wafer and 304 stainless substrates. Their crystalline structure, film surface morphology and optical properties, as well as anticorrosive behavior, were investigated. The structure and morphology of films were characterized by grazing-incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The optical properties were determined by spectroscopic ellipsometry (SE). The corrosion performances of the films were investigated through potentiostat and immersion tests in 1 M NaCl solutions. The results showed that as-deposited Ta2O5 thin films were amorphous. The refractive index varied from 2.06 to 2.17 (at 550 nm) with increasing operated pressure. The corrosion rate of Ta2O5 thin film improves as the operated pressure decreases. The Ta2O5 thin films deposited at 3 mTorr operated pressure could be exhibited high performance anticorrosive behavior.

We investigate the effect of central metal atom on the phthalocyanine (Pc) molecular crystals as intercalated with indium. As dopant, indium has physical interaction with some atom in the ring of Pc molecule and there is charge transfer between indium atom and Pc ring atom. Since In-doped Pc is a hole doping which increase positive charge carriers and the HOMO of ZnPc, CuPc, NiPc and MgPc are localized on the phthalocyanine ring, then, the central metal atom e.g. Zn, Cu, Ni and Mg are not directly involved with the charge transfer between indium dopant and their Pc molecule. The structural phase transition from α phase to β phase of ZnPc upon doping with indium is another evidence for the existing of charge transfer between dopant atom and matrix Pc molecule. A comparative experiment of optical absorption spectrum of each metal Pc reveals that the central metal atom will affect the forming of crystal structure whether will be α phase or β phase as intercalated with indium.

A new intercalation of Indium and Zinc Phthalocyanine(ZnPc) thin films is developed by using thermal co-evaporation method. Optical characteristics of In-doped ZnPc are studied in comparison with pristine ZnPc, which shows improvement on optical absorption at the visible spectrum. The presence of a new phase transition upon Indium doping is examined and consequently support the idea of the intercalated phase upon doping. A Schottky diode made of Indium doped ZnPc is fabricated in order to measure its electrical properties, its photo-current spectrum confirms the existence of phase transition.

A new intercalation of indium and nickel phthalocyanine(NiPc) thin films is developed by using thermal co-evaporation technique. X-ray diffractometer(XRD) and optical absorption spectroscopy of In-doped NiPc suggest the crystal structure of In-doped NiPc is α-phase as same as that of pristine NiPc. Current-voltage characteristic of Shottky diode fabricated with In-doped NiPc thin film shows the enhancement of charge carrier concentration due to indium doping. Further photoelectron spectroscopy experiments prove that In-doped NiPc is hole transport material.

A new intercalation of Indium and zinc phthalocyanine(ZnPc) thin film is developed by using thermal co-evaporation technique. The exciton dissociation at the interface of Indium Tin Oxide(ITO) electrode and Indium doped ZnPc upon laser irradiation is observed through the transient photovoltage measurement technique in comparison with the interfacial exciton dissociation occurred at ITO/pristine ZnPc interface. The occurring transient photovoltage spike is regarded as the effect of exciton dissociation at ITO/In-doped ZnPc interface and depends on the amount of free carrier separation by built-in field or charge carrier concentration according to doping ratio. The experiments demonstrate the existence of exciton dissociation at ITO/In-doped ZnPc interface, the direction of charges transfer is that holes are injected to ITO, whereas electrons are left in bulk film. A thin insulating layer of 6 nm thick lithium fluoride(LiF) is inserted between ITO and In-doped ZnPc to prevent the exciton dissociation at ITO/In-doped ZnPc interface and insist on the phenomenon of interfacial exciton dissociation. Further photoelectron spectroscopy experiments prove that In-doped ZnPc is hole transport material.

High sensitivity and very low drift rate pH sensors are successfully prepared by using nanocrystal-TiO2 as sensing membrane of ion sensitive field effect transistor (ISFET) device fabricated via CMOS process. This paper describes the physical properties and sensing characteristics of the TiO2 membrane prepared by annealing Ti and TiN thin films that deposited on SiO2/p-Si substrates through reactive DC magnetron sputtering system. The X-ray diffraction, scanning electron microscopy and Auger electron spectroscopy were used to investigate the structural and morphological features of deposited films after they had been subjected to annealing at various temperatures. The experimental results are interpreted in terms of the effects of amorphous-to-crystalline phase transition and subsequent oxidation of the annealed films. The electrolyte–insulator–semiconductor (EIS) device incorporating Ti O N membrane that had been obtained by annealing of TiN thin film at 850 °C exhibited a higher sensitivity (57 mV/pH), a higher linearity (1), a lower hysteresis voltage (1 mV in the pH cycle of 7 → 4 → 7 → 10 → 7), and a smaller drift rate (0.246 mV/h) than did those devices prepared at the other annealing temperatures. Furthermore, this pH-sensing device fabrication process is fully compatible with CMOS fabrication process technology.

Local structure of indium oxynitride thin films grown on silicon substrates was investigated by X-ray absorption fine structure technique incorporated with first principle calculations. The thin films were grown by using reactive gas timing radio frequency (RF) magnetron sputtering technique with nitrogen (N2) and oxygen (O2) as reactive gasses. The reactive gasses were interchangeably fed into sputtering system at five different time intervals. The gas feeding time intervals of N2:O2 are 30 : 0, 30 : 5, 30 : 10, 30 : 20 and 10 : 30 s, respectively. The analysis results can be divided into three main categories. Firstly, the films grown with 30 : 0 and 30 : 5 s gas feeding time intervals are wurtzite structure indium nitride with 25 and 43% oxygen contaminations, respectively. Secondary, the film grown with 10 : 30 s gas feeding time intervals is bixbyite structure indium oxide. Finally, the films are alloying between indium nitride and indium oxide for other growth condition. The fitted radial distribution spectra, the structural parameters and the combination ratios of the alloys are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

The electrical properties of flexible organic-inorganic bistable devices fabricated with aluminum (Al) sandwiched between tris-(8-hydroxyquinoline) aluminum (Alq3) and zinc selenide (ZnSe) layers were investigated. Current–voltage (I–V) measurements were conducted under conditions before, during, and after bending while changing the bending distance of the base plastic polyethylene terephthalate (PET) systematically. The maximum ON/OFF current ratios of the flexible bistable devices at flat and bent conditions were approximately 2.7×104 and 1.9×104, respectively. The conduction mechanisms in both ON and OFF states were analyzed by a theoretical model.

Water-soluble chitosan intercalated montmorillonite (wCTS/MMT) nanocomposites were modified and characterized by using Fourier transform infrared, thermogravimetric analysis, and X-ray diffractometer techniques. Two types of wCTS, namely, low molecular-weight chitosan (L-wCTS) and hydroxyethylacryl chitosan (H-wCTS) were synthesized and applied. The batch adsorption experiments on these nanocomposites were conducted by using basic dyes, that is, Basic Blue 66 and Basic Yellow 1 (BY1). The adsorption capacities of sodium montmorillonite (Na-MMT), chitosan, L-wCTS/MMT, and H-wCTS/MMT were measured and compared. The results showed that the adsorption capacities of wCTS/MMT nanocomposites were higher than those values of Na-MMT and chitosan. The adsorption kinetics of wCTS/MMT nanocomposites for BY1 were studied. It was described that the adsorption processes were better fitted by pseudo-second-order equation. The Langmuir and the Freundlich models were used to fit the adsorption isotherm. It was indicated that the adsorption isotherms followed the Langmuir model. The values of the maximum adsorption capacity of L-wCTS/MMT and H-wCTS/MMT adsorbents were at 188.7 and 294.1 mg/g, respectively. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 879-887, 2013

It is known that when green fruits such as bananas and mangoes grow from the immature to the ripe stages, their color changes from green to yellow. However, once the green fruits are yellow, it is difficult to classify them into the ripe and the overripe stages. Here, we propose and experimentally demonstrate for the first time a two-dimensional banana ripeness level sensor by using a cell phone. Our key approach relies on simultaneous analysis of two broad-spectral images of the banana under white light and ultraviolet illuminations. Particularly, our selected color ratios from these two broad-spectral images are used for spatially and specifically classifying the whole banana into immature, ripe, and overripe zones. Experimental proof of concept using a smart mobile phone is highlighted, featuring fast response, portability, and ease of implementation.

In this work, we report on the electrical properties of dye-doped colour tunable organic light-emitting diode (OLED). The device structure is glass substrate/indium tin oxide/N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) 30 nm/Alq3:DCM 50 nm/Aluminum (Al) 150 nm where NPB is the hole transport layer. Alq3:DCM is the emitting layer which made of tris(8-hydroxyquinoline) aluminium (Alq3) doped with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethyl-aminostyryl)-4H-pyran (DCM) organic dye. The influence of doping concentration has been investigated by current density–voltage measurement, luminance intensity–voltage characteristic, electroluminescence (EL) and impedance spectroscopy, respectively. The EL spectrum exhibits the shifted of peak position from green to red region. The threshold voltage of the device decreased at the low DCM doping concentration (1 wt.%), in contrast, when the increase in the doping concentrations then the threshold voltage will be increased. The highest luminance intensity and lowest turn-on voltage of OLED can be observed at doping concentration about of 1 wt.% of DCM. The impedance characteristics of the dye-doped OLED can be modelled by simply adopting the conventional equivalent circuit with the simple combination of resistors and capacitors network. © 2012 Canadian Society for Chemical Engineering