Zinc Oxide Semiconductor Research Articles

Synthesize of gadolinium-doped ZnO nano particles for energy applications by enhance its optoelectronic properties

In recent research, the zinc oxide (ZnO) semiconductor nano particles have received a lot of attention due to its unique physical, chemical, magnetic and optoelectronic properties. The present study focuses on the photo physical and optoelectronic properties of ZnO nanostructures. To attain better optical and optoelectronic properties for light emitting diodes, solar cells and photo detectors, the rare earth transition metal ions, specifically gadolinium (Gd) were doped into ZnO nano material. Gadolinium-doped ZnO nano materials have been synthesized by a simple chemical deposition method. The structural, morphological, optical properties of synthesized samples have been investigated by various techniques, including x-ray diffraction (XRD), UV-absorption spectroscopy, and photo luminescence spectroscopy. X-ray diffraction analysis confirmed the formation of pure single phase with a particle size in the range of 30–42 nm. Optical absorption studies demonstrates that the absorption edge of the Gd:ZnO appeared to shift towards the longer wavelength due to the charge transfer between the ZnO valence or conduction band and rare earth ion 4f energy level. The band gap of the doped ZnO samples was found to be decreases and it varies from 3.2 eV to 3.1 eV due to the quantum confinement of the charge carriers in ZnO. These results provide a new approach to design ZnO nano particles with enhanced photochemical properties, light emitting electronics and solar cells.

Efficient luminomagnetic and conductive Eu and Dy doped ZnO phosphors for multifunctional devices

In this study, europium (Eu) and dysprosium-(Dy) doped phosphors, i.e., ZnO:Eu, ZnO:Dy, and Eu:Dy co-doped zinc oxide (ZnO:Eu, Dy) semiconductor phosphors, with optimized concentrations, were synthesized using the conventional solid-state reaction method in an oxygen environment. Detailed structural, morphological, and compositional investigations were conducted using X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray measurements, respectively. Photoluminescence (PL) emission spectra were recorded under different excitation wavelengths to assess the optical characteristics. Electrical analysis was conducted using an inductance (L), capacitance (C), and resistance (R) (LCR) meter and a Keithley source meter, and magnetic analysis was performed using a vibrating sample magnetometer (VSM). XRD confirmed the presence of Eu and Dy ions because the diffraction peaks matched perfectly with those for Eu2O3 and Dy2O3, respectively. The PL results indicated the broad emissions from the samples in the visible region (400–700 nm) under different ultraviolet excitation wavelengths. The VSM results demonstrated that both the Dy-doped and Eu:Dy co-doped ZnO samples exhibited paramagnetic behavior at room temperature, but not the undoped and Eu-doped ZnO samples. The ZnO:Dy sample had superior parameters in terms of the electrical measurements such as the AC/DC conductivity, capacitance, current density, and dielectric constant compared with the ZnO:Eu and ZnO:Eu, Dy samples. These detailed investigations of the optical, magnetic, and electrical properties demonstrate that ZnO:Dy and ZnO:Eu, Dy may be promising materials for use in optical devices.

Enhanced bactericidal performance of nickel oxide-zinc oxide nanocomposites synthesized by facile chemical co-precipitation method

Nanocomposites based on nickel oxide and zinc oxide (NiO–ZnO) semiconductors have gained pronounced attention in several areas rather than in antibacterial applications. Present investigation is devoted to synthesis NiO–ZnO nanocomposites with different concentrations (0.03, 0.06, 0.09 and 0.12 M) of Ni2+ ions by a facile chemical co-precipitation method. UV-Visible spectral analysis revealed that absorption band edge of pristine ZnO nanoparticles is red shifted to visible region due to incorporation of Ni2+ ions in Zn2+ sites of ZnO lattice. Band gap energy of NiO–ZnO nanocomposites is decreased owing to induction of strain in crystal lattice. Photoluminescence results disclosed that high concentrations of Ni2+ ions in NiO–ZnO nanocomposites improve distortion centers and lattice surface defects in ZnO and as a consequence that minimizes defect related emissions. X-ray diffraction patterns exhibited diffraction peaks corresponding to face-centered cubic NiO and hexagonal wurtzite structured ZnO. Energy dispersive X-ray spectroscopy analysis indicated presence of Ni, Zn and O elements in the nanocomposites and confirmed their purity. Field emission scanning and high resolution transmission electron microscopy images signified composite morphology of NiO–ZnO nanocomposites containing randomly oriented nanorods decorated with nanoparticles. Enhanced bactericidal activity of NiO–ZnO nanocomposites over pristine ZnO nanoparticles against selected bacterial species can be ascribed to increase in surface area, decrease in crystalline size and higher reactive oxygen species generation after modification by Ni2+ ions. Based on this pronounced bactericidal activity, it is concluded that NiO–ZnO nanocomposites can be potentially employed as bactericidal agents against pathogenic bacterial species.

Conductivity and Electrochemical Behavior of Plasticized Polymer Electrolyte for Dye-Sensitized Solar Cell Integrated Supercapacitor

Abstract The current energy situation requires not only enormous energy in a brief period of time but clean energy as well. In this direction, a dye-sensitized solar cell (DSSC)—supercapacitor (SC) integrated energy device has been fabricated. This embedded energy system has a specific advantage such as easy manufacturing, low manufacturing costs, and flexible substrates compatibility. A natural photosensitizer was extracted from readily available beetroots and characterized using ultraviolet (UV)-visible spectroscopy. The zinc oxide semiconductor was synthesized using microwave technique and regarded as the DSSC photoanode material. The ZnO’s phase, purity, and morphology were investigated using X-ray diffraction (XRD) spectroscopy and scanning electron microscope. The iodine-doped cellulose acetate propionate (CAP) biopolymer electrolyte functions as the DSSC and supercapacitor electrolyte. The solid polymer electrolyte conductivity and dielectric studies were performed using electrochemical impedance spectroscopy (EIS). The laser-induced technique was used to synthesize graphene that plays a dual purpose as photocathode in DSSC and supercapacitor electrodes. The embedded energy unit from the DSSC-supercapacitor demonstrates a 6.75% fill factor representing its decent efficiency.

Transparent Flexible Nanoline Field-Effect Transistor Array with High Integration in a Large Area.

Transparent flexible transistor array requests large-area fabrication, high integration, high manufacturing throughput, inexpensive process, uniformity in transistor performance, and reproducibility. This study suggests a facile and reliable approach to meet the requirements. We use the Al-coated polymer nanofiber patterns obtained by electrohydrodynamic (EHD) printing as a photomask. We use the lithography and deposition to produce highly aligned nanolines (NLs) of metals, insulators, and semiconductors on large substrates. With these NLs, we demonstrate a highly integrated NL field-effect transistor (NL-FET) array (105/(4 × 4 in2), 254 pixel-per-inch) made of pentacene and indium zinc oxide semiconductor NLs. In addition, we demonstrate a NL complementary inverter (NL-CI) circuit consisting of pentacene and fullerene NLs. The NL-FET array shows high transparency (∼90%), flexibility (stable at 2.5 mm bending radius), uniformity (∼90%), and high performances (mobility = 0.52 cm2/(V s), on-off ratio = 7.0 × 106). The NL-CI circuit also shows high transparency, flexibility, and typical switching characteristic with a gain of 21. The reliable large-scale fabrication of the various NLs proposed in this study is expected to be applied for manufacturing transparent flexible nanoelectronic devices.

Recent developments in electrospun ZnO nanofibers: A short review

Especially for the potential use as sensors, but also in all other applications in which an interaction with the environment occurs, nanofibrous materials are advantageous due to their large specific surface area. An interesting material for electrospinning is the semiconductor zinc oxide (ZnO) which is often used in photoelectric or sensory applications. Nanofibers containing ZnO can be produced, for example, by electrospinning polyvinylpyrrolidone/zinc nitrate from a dimethylformamide/ethanol solution, followed by calcination to remove the organic phase. Alternatively, the polymer/semiconductor blended nanofibers can be used which are often less brittle, but on the other hand offer less contact between ZnO and the environment. Finally, decorating a nanofiber mat with ZnO offers another possibility to prepare nanofibers with ZnO surface. Possible applications of electrospun ZnO nanofibers or nanofiber mats include gas sensing, microwave absorption, photocatalytic degradation or enhancement of supercapacitor electrodes. This short review gives an overview of the most recent electrospinning and after-treatment techniques to create pure and blended ZnO nanofibers and presents the broad variety of possible applications of this well-known semiconductor with some still surprising properties.

Effect of ZnO dispersion in optical and structural of nematic liquid crystal

Incorporation of zinc oxide (ZnO) semiconductor particles in liquid crystal technology is advantageous due to its unique optical properties especially in ultraviolet region. In this paper, optical and film morphology of nematic liquid crystal films, 4′-(hexyloxy)-4-biphenylcarbonitrile (6OCB) were analyzed using UV-Vis absorption spectroscopy, z-scan measurement, Raman spectroscopy and X-ray powder diffraction. As expected, dramatic change of absorption in both ultraviolet and visible region were observed upon additional weightage of ZnO particles into the 6OCB mixture. Z-scan measurement obtained under 532 nm CW laser line was used to study nonlinear refractive index, n2 of the material. This ZnO particles incorporation in 6OCB mixture show self-defocusing property with thermal effects as one of its origin of nonlinear absorption occurring at 532 nm. Prominent diffraction peaks of 15°, 29°, 31°, 35° and 47° were measured from rubbed films of 6OCB doped ZnO films which indicated 6OCB and ZnO lattice crystal structures. Microscopic formations of 6OCB molecules is highly dependent with the proximity to the ZnO particle as analyzed by Raman vibrational analysis. These findings can be used to suggest optical and electrical improvement to the liquid crystal film in optoelectronics application as electro-optic modulator and optical switch.

Bi-doping improves the magnetic properties of zinc oxide nanowires.

Room-temperature ferromagnetism in the large and direct bandgap diluted magnetic semiconductor zinc oxide (ZnO) is attributed to the intrinsic defects and p-orbital–p-orbital (p–p) coupling interaction. However, due to oxidation, the ferromagnetism induced by defects is unstable. In the present work, the solution process synthesis route was utilized to grow pristine and bismuth-doped, highly crystalline ZnO nanowire (ZnO NW)-based samples. The FE-SEM images showed that the grown ZnO NWs have a preferred orientation along the c-axis in the (001) direction due to the anisotropic crystal nature of ZnO. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Bi, and at a higher doping content, the bismuth oxide phase appeared. The XRD patterns showed the wurtzite crystal structure, and the large intensity of the (002) peak suggests that most of the reflection was from the top hexagonal face of the NWs, and thus, the wires are predominantly aligned along the c-axis. The TEM analysis further confirmed the crystal growth direction along the (001) direction. The UV-Visible absorption and PL measurements also showed a decrease in the bandgap with an increase in doping concentration, which may be associated with the sp–d exchange interaction between the localized d-electrons and band electrons of the Bi ions. Bi-doping tended to increase the PL intensity in the visible region. The magnetic properties measured by SQUID at 4 and 300 K showed ferromagnetic behaviour for both the pristine and Bi-doped samples. However, the saturation magnetization for the Bi-doped samples was higher compared to that of the pristine ZnO samples until the threshold doping value. The obtained results demonstrated that Bi-doping can be used to tune both the optical and magnetic properties of ZnO NWs, hence paving the way for future spintronics and spin-polarized optoelectronics applications.

Biosynthesis of Zinc Oxide Nanoparticles From Plectranthus Amboinicus and Its Photocatalytic Effect on Wastewater Treatment

Photocatalysis using semiconductor Zinc Oxide (ZnO) is a promising technology for water purification. The current work is aimed at improving the reduction of organic carbon of domestic wastewater by a combination of photocatalysis and Green synthesis. Synthesized zinc oxide nanoparticles from Plectranthus amboinicus was characterized by UV spectroscopy, FTIR, SEM, and XRD. Degradation of organic matter in effluent using Zinc Oxide and Plectranthus amboinicus was examined by the photocatalytic reaction. The reduction of organic carbon was analyzed by COD and pH analysis on synthesized ZnO nanoparticles. The decrease in COD from 800 mg/l to 50 mg/l and an increase in pH from 6.8 to 7.4 results in degradation of organic matter in the effluent. These advantages enable us to reuse the treated water for various purposes such as flushing, gardening, cleaning

An Energy-Efficient Normally Off Microcontroller With 880-nW Standby Power, 1 Clock System Backup, and 4.69-$\mu$ s Wakeup Featuring 60-nm CAAC-IGZO FETs

This letter presents a microcontroller unit (MCU) that employs a $c$ -axis aligned crystalline indium–gallium–zinc oxide semiconductor FET (CAAC-IGZO FET) with an extremely low off-state current below the zepto-ampere (10−21 A) level. This MCU based on IGZO-FETs has logic circuits and memory macros that can retain data even when the power supply is turned off, and internal voltage regulators that store the reference voltage. A prototype chip has been fabricated with a monolithic process that combines an IGZO process (embedded in BEOL) and an Si CMOS process; the chip has a standby power of 880 nW, a system backup time of 21 ns with 44 fJ/bit, and a wakeup time of $4.69~\mu \text{s}$ . The fabricated chip has demonstrated that the highly energy-efficient normally off computing that establishes low-power operations in Internet of Things and edge AI computing can be achieved with IGZO technology.

Mechanisms behind slow photoresponse character of Pulsed Electron Deposited ZnO thin films

Semiconducting Zinc Oxide (ZnO) is ideal candidate for ultraviolet (UV) photodetector due to its promising optoelectronic properties. Photoconductive type ZnO photodetectors, which is fabricated in metal-semiconductor-metal configuration, show mostly very high photoconductivity under UV light, but they are plagued by slow photoresponse time as slow as several tens of hours, even more. Most of the studies claimed that atmospheric adsorbates such as water and oxygen create charge traps states on the surface and remarkably increase both the photoconductivity and response time. There are also limited studies, which claim that the defect states acting as hole trap centers prolong response time significantly. However, the underlying physical mechanism is still unclear. Here we study the effects of both adsorbates and defect-related states on the photoresponse character of Pulsed Electron Deposited ZnO thin films. In order to distinguish between these two mechanisms, we have compared the time-dependent photoresponse measurements of bare-ZnO and SiO2 encapsulated-ZnO thin film samples taken under UV light and high vacuum. We show that the dominant mechanism of photoresponse in ZnO is the adsorption/desorption of oxygen and water molecules even when the measurement is performed in high vacuum. After the encapsulation of sample surface by a thin SiO2 layer, the adsorption/desorption rates can significantly improve, and the effects of these molecules partially removed.

Electro-thermal synergetic effect in 0.94Bi0.5Na0.5TiO3-0.06BaZr0.2Ti0.8O3: ZnO pyroelectric composites for high-performance thermal energy harvesting

Pyroelectric energy harvesters based on lead-free ceramics cannot meet the requirement for practical applications due to their low energy conversion capacity. In this work, high-performance thermal energy harvesting with the greatly enhanced pyroelectric coefficient and rate of temperature change has been achieved by compositing the zinc oxide (ZnO) semiconductor into 0.94Bi0.5Na0.5TiO3-0.06BaZr0.2Ti0.8O3 (BNT-BZT) ceramic matrixes. The ZnO semiconductor not only provides charge carriers for accelerating the transportation of free charge to improve the pyroelectric coefficient of BNT-BZT: ZnO but also enhances the temperature variation rate dT/dt of the samples because of its high thermal conductivity. Owing to the electrothermal synergetic effect of the ZnO semiconductor, a highly improved energy harvesting performance of the energy density reaching up to 130 μJ cm−3 is achieved, which is over three times compared to that of the pristine BNT-BZT ceramics. This work will provide an effective and facile approach to develop high-performance pyroelectric composite ceramics for thermal energy harvesting applications.

The role and mechanisms of zinc oxide nanoparticles in the improvement of the radiosensitivity of lung cancer cells in clinically relevant megavoltage radiation energies in-vitro

Objective(s): Semiconductor zinc oxide nanoparticles (ZnO NPs) have unique properties, such as inherent selectivity and photosensitization effects under ultraviolet (UV) radiation. ZnO NPs serve as promising anticancer agents. However, UV radiation limits their penetration into the body. In most clinical settings, it is essential to use high-energy photons in the treatment of deep-seated tumors. The present study aimed to evaluate the radiosensitization effects of ZnO NPs on human lung cancer cells under megavoltage (MV) X-ray irradiation. Materials and Methods: ZnO NPs with the mean diameter of seven nanometers were synthesized and characterized. The cytotoxicity and cellular uptake of ZnO NPs were evaluated in SKLC-6 lung cancer and MRC-5 normal lung cells using the 3-(4,5-dimethylthiazol-yl)-5(3-carboxymethoxyphenyl)-2H-tetrazolium (MTT) and inductively coupled plasma-mass spectrometry assays, respectively. In addition, the radiosensitization effects of ZnO NPs were investigated under MV irradiation using a clonogenic survival assay. Apoptosis induction and DNA damage were also evaluated using flow cytometry and cytokinesis-block micronucleus assay, respectively.Results: ZnO NPs were taken up and reduced the viability of the cancer cells at a higher rate compared to the normal cells. Moreover, ZnO NPs significantly enhanced the radiosensitivity of the cancer cells with the sensitizer enhancement ratios of 1.23 and 1.31 at the concentrations of 10 and 20 μg/ml, respectively. However, they had no significant effect on the radiosensitivity of the normal cells. Apoptosis induction and DNA damage also improved at a higher rate in the cancer cells compared to the normal cells with the combination of ZnO NPs with MV radiation.Conclusion: According to the results, ZnO NPs had the potential to be a selective radiosensitizer for lung cancer radiotherapy under MV X-ray irradiation. Some of the cytotoxic and genotoxic mechanisms in radiosensitization by ZnO NPs were elevated apoptosis induction and DNA damage levels.

Effects of praseodymium doping on the electrical properties and aging effect of InZnO thin-film transistor

Amorphous indium gallium zinc oxide is a popular semiconductor candidate for amorphous oxide semiconductor thin-film transistors in the field of flat-panel display. However, the existence of gallium component restricts the enhancement of mobility dramatically. In this study, we report a new praseodymium (Pr) dopant as a stabilizer in amorphous indium zinc oxide semiconductor (IZO) with high mobility and stability. Meanwhile, the PrIZO TFTs were fabricated to investigate the effects of Pr on electrical properties, stability and aging effect. The optimal PrIZO TFT exhibited a desired performance with a saturation mobility (μsat) of 25.8/32.6 cm2 V−1 s−1, an Ion/Ioff ratio of 3.5 × 107/5.4 × 107, a subthreshold swing value of 0.14/0.13 V dec−1 and a threshold voltage (Vth) of 2.9/2.1 V, respectively, before and after an air environment storage period of 90 days without passivation layer, which exhibits lower sensitivity of the channel region to oxygen/moisture from the atmosphere than IZO TFT. XRD analysis revealed that the Pr dopant had no effect on the amorphous state of IZO thin film with annealing up to 400 °C. XPS analyses suggested that the fraction of oxygen vacancy subpeak decreased significantly with Pr incorporated into IZO. The μ-PCD decay analyzation and the subgap density of states indicate that acceptor-like trap states induced by Pr ions lead to the suppression of ambient-induced excess carrier in conduction band. This work is anticipated to provide a kind of reliable stabilizer for amorphous oxide semiconductor without deteriorating mobility significantly.

Effects of Transition Energy on Intra-Band Photoluminescence of Zinc Oxide (ZnO) Semiconductor under Low injection Level

This paper presents the effects of the transition energies on photoluminescence intensities in Zinc Oxide compound semiconductor due to the intra-band transition of free carriers. The excitation of free carriers from the valence band to conduction band and from different localized state to the conduction band by the illumination of sufficient energy is considered. A theoretical model for minority carrier trapping is also investigated to explain the dependence of the photoluminescence on the trap energy. Variation of photoluminescence intensities along with localized state energy and transition energy is considered at different temperatures. As temperature increases the photoluminescence due to the transition of free electrons from the conduction band to the valence band, from the conduction band to the localized states and from the localized states to the valence band are increasing.

Electrical, Optical and Electrochemical Corrosion Resistance of AZO, GZO, AGZO Films Depending on the Hydrogen Content.

Zinc oxide (ZnO) is a commonly used material for the front contact layer of thin film solar cells based on chalcopyrite CuInGaSe₂ (CIGS), since it satisfies the optical and electrical properties with low cost and is abundantly available. For high-performance, the front contact electrode in the CIGS solar cell should have low resistivity and high transmittance. Hence, efforts to improve ZnO's electrical and optical properties have been widely carried out. The corrosion resistance of the front contact film, however, has not been studied well. So, this paper compared the electrochemical stability of ZnO based transparent conducting oxide (TCO) films such as aluminum zinc oxide (AZO), gallium zinc oxide (GZO) and aluminum gallium zinc oxide (AGZO) grown in H₂. All films predominately grew in the (002) c-axis direction and their crystallites improved with increasing H₂ ratio, reflecting the enhanced electrical properties. Hydrogen acts as a shallow donor in the n-type ZnO semiconductor and increases carrier densities by forming oxygen vacancies by combining with oxygen molecules to form OH- functionalities. The electrochemical corrosion resistance of prepared films showed a linear improvement with increasing hydrogen. This change was attributed to the grain morphology and size and resulting grain boundaries. Since corrosion occurs mainly at grain boundaries, corrosion resistance seems to be better with a lower density of grain boundaries, due to larger grains caused by hydrogen. Electric conductivity was better in the order of GZO > AGZO > AZO, while corrosion resistance was in the reverse order. By adding hydrogen, the electrical resistivity of AGZO improved to near GZO, and the corrosion resistance was also enhanced to near AZO.

Simple Combustion Synthesis, Structural, Morphological, Optical and Catalytic Properties of ZnO Nanoparticles

In this present study, semiconductor zinc oxide (ZnO) nanoparticles were successfully prepared by microwave irradiation (ZnO-MIM) and conventional combustion (ZnO-CCM) method, respectively using Aloe vera plant extract as reducing agent. Crystal structure, purity and surface morphology of the samples were examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectral studies was used to analysis the optical property and band gap energy of the samples. The antibacterial activities of ZnO nanostructures (ZnO-MIM and ZnO-CCM) were tested against both gram positive (Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Proteus mirabilis, Salmonella typhi) by modified disc diffusion method and observed enhanced activity against P. mirabilis and S. typhi. ZnO nanostructures (ZnO-MIM and ZnO-CCM) were used as the photo-catalysts for the degradation of methylene blue (MB) dye and observed enhanced efficiency of degradation of MB than that of their same bulk materials. Moreover, the synthesis method is easy with low cost and time consumable and also high yield purity products.

Electrical and electrochemical behavior of a zinc-rich epoxy coating system with carbon nanotubes as a diode-like material

Non-conventional responses in the impedance spectra of a zinc-rich coating system were observed in electrical and electrochemical impedance measurements that have previously been considered to have no effect on the system. Despite the impressive progress in zinc-rich coating systems to control corrosion in metal structures through galvanic effects, some physical properties influencing the responses of electrochemical systems remain unexplored. Electrochemical and non-electrolytic cells on zinc-rich (55 vol%) coatings with multi-wall carbon nanotube systems were analyzed to determine the intrinsic response of the coating with electrical passive and active analogs under electrical conditioning cycles. In the dry condition, the impedance spectra of the carbon nanotube-added zinc-rich coating showed increased electrical resistance of the film under consecutive cyclic testing. The non-conventional response of the increase in impedance was studied by determining the impedance responses under various temperatures and bias potentials and performing a current-voltage method. The non-conventional phenomenon was found to be caused by an increased barrier height between the semiconducting zinc oxide material and metal, which is susceptible to an external electrical field. During immersion, the change in impedance of the zinc-rich primer (ZRP) film under consecutive electrochemical sequences differed from that under natural degradation. This non-conventional response of the ZRP coating was influenced by the applied bias potential. The capacitive behavior influenced by the zinc corrosion products in the coating had a longer relaxation time, thus decreasing the open circuit potential. To understand this phenomenon, we propose a charging-relaxation potential model. In addition, the potential exhibited a change in the electrical resistance of the ZRP film during consecutive electrochemical testing.

Exploration of interfacial dynamics in squaraine based nanohybrids for potential photodynamic action

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure exhibiting cytotoxic effects toward malignant cells. Hydrophobic nature of most photosensitizers used in PDT with lower light absorption ability restricts practical use of PDT. Herein, we have employed a squaraine drug (SQ) with 665 nm absorbance peak maxima as the photosensitizing agent and evaluate its photo-physical properties. The tendency of aggregation formation in aqueous media limits its practical usefulness. Thus, we have synthesised wide band gap semiconductor zinc oxide (ZnO) nanoparticles and functionalized the surface using squaraine molecules. The molecular cross-talking was evaluated using excited state fluorescence lifetime decay profiles and by employing Fӧrster resonance energy transfer (FRET) technique. The nanohybrids show improvement in three aspects compared to bare SQ molecule such as lesser aggregate formation in aqueous media, pH responsive precipitation of the drug and improvement of photo-induced reactive oxygen species (ROS) generation. Ultrafast dynamical study at the inorganic (ZnO) - organic (SQ) interface depicts presence of photo-induced charge transfer process at the junction which indeed improves the ROS generation capability. Finally, the photodynamic action has been evaluated in human breast cancer cell line MCF-7. The nanohybrids depict enhanced photo toxicity in cancer cell with loss of adherence and typical morphology of cancerous cell depicting controlled cell death. The present study employ characterisation of nanohybrids for potential use in PDT for cancer treatment.

Intense Pulsed Light Annealing Process of Indium-Gallium-Zinc-Oxide Semiconductors via Flash White Light Combined with Deep-UV and Near-Infrared Drying for High-Performance Thin-Film Transistors.

In this study, an intense pulsed light (IPL) process for annealing an indium-gallium-zinc-oxide (IGZO) semiconductor was conducted via flash white light combined with near-infrared (NIR) and deep-ultraviolet (DUV) drying to form a thin-film transistor (TFT). The IGZO thin-film semiconductor was fabricated using a solution-based process on a doped-silicon wafer covered with silicon dioxide. In order to optimize the IPL irradiation condition for the annealing process, the flash white light irradiation energy was varied from 70 to 130 J/cm2. Drying by NIR and DUV irradiation was employed and optimized to improve the performance of the TFT during IPL annealing. A TFT with a bottom-gate and top-contact structure was formed by depositing an aluminum electrode on the source and drain on the IPL-annealed IGZO. The electrical transfer characteristic of the TFT was measured using a parameter analyzer. The field effect mobility of the saturation regime and on/off current ratio were evaluated. Changes of the metal-oxide bonds in the IGZO thin film were analyzed using X-ray photoelectron spectroscopy to verify the effect of NIR and DUV drying and IPL annealing. Also, the distributions of the carrier concentration on the IPL-annealed IGZO were measured through a hall-effect system to deeply investigate the transition of the electrical characteristic of the TFT. From the results, it was found that the bond between oxygen and the gallium compound was activated via DUV irradiation. The NIR- and DUV-assisted IPL-annealed IGZO-based TFT showed highly enhanced electrical performance with a 7.7 cm2/V·s mobility and a 3 × 106 on/off ratio.