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Highly arranged porous anodic titania (TiO2) nanotube arrays (ATNT) were fruitfully fabricated by the anodization of Ti foil in an ammonium fluoride electrolyte.

Because β-2-microglobulin (β

The super enhancement of silicon band edge luminescence when co-implanted with boron and carbon is reported. The role of boron in the band edge emissions in silicon was investigated by deliberately introducing defects into the lattice structures. We aimed to increase the light emission intensity from silicon by boron implantation, leading to the formation of dislocation loops between the lattice structures. The silicon samples were doped with a high concentration of carbon before boron implantation and then annealed at a high temperature to activate the dopants into substitutional lattice sites. Photoluminescence (PL) measurements were performed to observe the emissions at the near-infrared region. The temperatures were varied from 10 K to 100 K to study the effect of temperature on the peak luminescence intensity. Two main peaks could be seen at ~1112 and 1170 nm by observing the PL spectra. The intensities shown by both peaks in the samples incorporated with boron are significantly higher than those in pristine silicon samples, and the highest intensity in the former was 600 times greater than that in the latter. Transmission electron microscopy (TEM) was used to study the structure of post-implant and post-anneal silicon sample. The dislocation loops were observed in the sample. Through a technique compatible with mature silicon processing technology, the results of this study will greatly contribute to the development of all Si-based photonic systems and quantum technologies.

Physiological roles in human body system substantially supported by human serum albumin (HSA). Frequent monitoring of HSA level is vital in early diagnosis of HSA-related diseases. This work focuses on demonstrating field-effect transistor (FET)-based immunosensor utilizing high aspect ratio zinc oxide nanorods (ZnO NRs) as a transducer in quantifying HSA. The acetylacetonate-assisted hydrothermal method was used to synthesize ZnO NRs, and a standard photolithography process was applied to fabricate the FET device. The morphology and electrical evaluations of the ZnO NRs were performed using field emission scanning electron microscopy and current-voltage measurement system, respectively. The surface modification of the ZnO NRs was confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The detection mechanism is based on the covalent binding interactions between an antibody and HSA target that induced a change in the drain current (ID) of the fabricated biosensor. The biosensor exhibited a high sensitivity of 0.826 mA (g/ml)-1 with a LOD value of 9.81 ng/ml in a linear range between 10 ng/ml and 100 µg/ml. HSA was also successfully detected in the interference by other biomolecules in a real serum, indicating the capability of ZnO NRs-FET immunosensor for quantifying HSA in complex biological matrix. This biosensor also exhibits good stability after stored for 360 days.

The importance of nanotechnology in medical applications especially with biomedical sensing devices is undoubted. Several medical diagnostics have been developed by taking the advantage of nanomaterials, especially with electrical biosensors. Biosensors have been predominantly used for the quantification of different clinical biomarkers toward detection, screening, and follow-up the treatment. At present, ovarian cancer is one of the severe complications that cannot be identified until it becomes most dangerous as the advanced stage. Based on the American Cancer Society, 20% of cases involved in the detection of ovarian cancer are diagnosed at an early stage and 80% diagnosed at the later stages. The patient just has a common digestive problem and stomach ache as early symptoms and people used to ignore these symptoms. Micro ribonucleic acid (miRNA) is classified as small non-coding RNAs, their expressions change due to the association of cancer development and progression. This article reviews and discusses on the currently available strategies for the early detection of ovarian cancers using miRNA as a biomarker associated with electrical biosensors. A unique miRNA-based biomarker detections are specially highlighted with biosensor platforms to diagnose ovarian cancer.

Intravenous cannulation is experientially traumatic to children. To minimize this, EMLA® is applied on the would-be-cannulated area before IV cannula insertion. However, the time to achieve its maximum efficacy may be affected due to incomplete cutaneous absorption and the duration of application. The latter may be a limiting factor in a busy healthcare facility. The usage of dissolvable maltose microneedles may circumvent this problem by introducing micropores that will facilitate EMLA® absorption. A randomized phase II cross-over trial will be conducted to compare the Visual Analogue Scale (VAS) pain scores and skin conductance algesimeter index between 4 different interventions (1 fingertip unit (FTU) of EMLA® with microneedle patch for 30 min before cannulation; 0.5 FTU of EMLA® with microneedle patch for 30 min; 1 FTU of EMLA® with microneedle for 15 min; 1 FTU of EMLA® with sham patch for 30 min). A total of 26 pediatric patients with thalassemia aged between 6 and 18 years old and requiring blood transfusion will be recruited in this trial. During the visits, the VAS scores and skin conductance algesimeter index at venous cannulation will be obtained using the VAS rulers and PainMonitor™ machine, respectively. The trial will commence in August 2021 and is anticipated to end by August 2022.

Biosensors operating based on electrical methods are being accelerated toward rapid and efficient detection that improve the performance of the device. Continuous study in nano- and material-sciences has led to the inflection with properties of nanomaterials that fit the trend parallel to the biosensor evolution. Advancements in technology that focuses on nano-hybrid are being used to develop biosensors with better detection strategies. In this sense, titanium dioxide (TiO2) nanomaterials have attracted extensive interest in the construction of electrical biosensors. The formation of TiO2 nano-hybrid as an electrical transducing material has revealed good results with high performance. The modification of the sensing portion with a combination (nano-hybrid form) of nanomaterials has produced excellent sensors in terms of stability, reproducibility, and enhanced sensitivity. This review highlights recent research advancements with functional TiO2 nano-hybrid materials, and their victorious story in the construction of electrical biosensors are discussed. Future research directions with commercialization of these devices and their extensive utilizations are also discussed.

In this study, we demonstrated the fabrication of the concave conic shape microneedle with the aid of COMSOL Multiphysics simulation. The stress and buckling of the microneedle structure were simulated by applying various loads ranging from 50 to 800 g perpendiculars to the tip in order to predict the occurrence of microneedles structure deformation. The simulation study indicated that the surface buckling deformation does not occur to the microneedle structure with the increment of the load. The microneedles with dimensions of height and diameter tip ranging from 60 to 100 μm and 1 to 4 μm, respectively had been fabricated via an etching process in a mixture of hydrofluoric acid, nitric acid, and acetic acid. Three optimized microneedles but different in the structures were fabricated via the acidic etching process. The reproducibility of 3 different microneedle structures was 15, 20, and 60%, respectively. Stress and buckling analyses of the fabricated microneedles were further carried out on the rat skin. The obtained experimental results show promising applications for the deep dermis, stratum corneum to epidermis layer penetration.

An AlGaN/GaN/Si high electron mobility transistor (HEMT) using a GaN:C buffer with a 2 nm AlGaN electron-blocking layer (EBL) is investigated for the first time for millimeter-wave applications. Compared with the double heterostructure field effect transistor (DHFET), the AlGaN/GaN HEMT with the GaN:C/EBL buffer has a lower vertical leakage, higher thermal stability, and better RF performance. In addition, AlGaN EBL can prevent carbon-related traps from GaN:C and improve electron confinement in 2DEG during high-frequency operation. Finally, a Pout of 31.2 dBm with PAE of 21.7% were measured at 28 GHz at 28 V. These results demonstrated the great potential of HEMTs using GaN:C with AlGaN EBL epitaxy technology for millimeter-wave applications.

Nanoelectronics holds significant promise for two-dimensional (2D) semiconducting transition metal dichalcogenide (TMD) applications. On a polycrystalline WS2 monolayer created by metal-organic chemical vapor deposition (MOCVD) at 950 °C, we studied the nucleation, growth, and development of Al2O3 atomic layer deposition (ALD) on a SiO2/Si substrate. In this investigation, we used various complementary characterization methods, such as Raman spectroscopy, elastic recoil detection, atomic force microscopy, and time-of-flight secondary ion mass spectrometry, to understand thoroughly the intrinsic reactivity of WS2. Strong peak intensity changes at the interfaces in the Raman line scans of the SiO2/Si patterns suggest extremely crystalline WS2. After multiple ALD cycles, triangular WS2 crystals were decorated to provide a two-dimensional growth mode with a great selectivity for grain boundaries and step edges. The results of this work can be used for further exploration of the TMD monolayer structure and properties, which is essential for tailoring 2D materials for a specific application in devices.

Substrate voltage (VSUB) effects on GaN-on-Si high electron mobility transistors (HEMTs) power application performance with superlattice transition layer structure was investigated. The 2DEG conductivity and buffer stack charge redistribution can be affected by neutral/ionized donor and acceptor traps. As the donor/acceptor traps are excessively ionized or de-ionized by applying VSUB, the depletion region between the unintentionally doped (UID)/Carbon-doped (C-doped) GaN layer may exhibit a behavior similar to the p–n junction. An applied negative VSUB increases the concentration of both the ionized donor and acceptor traps, which increases the breakdown voltage (BV) by alleviating the non-uniform distribution of the vertical electric field. On the other hand, an applied positive VSUB causes the energy band bending flattener to refill the ionized traps and slightly improves the dynamic Ron degradation. Moreover, the amount of electrons injected into the buffer stack layer from the front side (2DEG channel/Ohmic contact) and the back side (AlN nucleation layer/superlattice transition layer) are asymmetric. Therefore, different VSUB can affect the conductivity of 2DEG through the field effect, buffer trapping effect, and charge redistribution, which can change the electrical performance of the device.

In this work, a low-power plasma oxidation surface treatment followed by Al2O3 gate dielectric deposition technique is adopted to improve device performance of the enhancement-mode (E-mode) AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs) intended for applications at millimeter-wave frequencies. The fabricated device exhibited a threshold voltage (Vth) of 0.13 V and a maximum transconductance (gm) of 484 (mS/mm). At 38 GHz, an output power density of 3.22 W/mm with a power-added efficiency (PAE) of 34.83% were achieved. Such superior performance was mainly attributed to the high-quality Al2O3 layer with a smooth surface which also suppressed the current collapse phenomenon.

In this study, surface modification of a silane-crosslinked polyethylene (Si-XLPE) compound was carried out by gliding arc atmospheric plasma. Samples were exposed to the plasma for different durations and the plasma-induced alterations of the surfaces were comprehensively assessed. Surface chemistry was evaluated initially via Fourier transform infrared spectroscopy (ATR-FTIR) and energy-dispersive X-ray (EDX) analysis. Surface morphology was investigated by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). For calculating surface free energy (SFE), contact angle measurement (CAM) was performed. In order to have accurate details on the surface chemistry and morphology, X-ray photoelectron spectroscopy (XPS) and Grazing Incidence X-ray Diffraction (GIXRD) analysis were conducted, respectively. Results revealed that this modification method doubled the amount of atomic oxygen and nitrogen on the surface, indicating the formation of polar chemical components on the surface. Moreover, plasma could change the surface morphology considerably by selective etching and impacting on roughness. Furthermore, it was observed that the modification improved the surface crystallinity to some extent and also increased SFE drastically. Surface modification of Si-XLPE by gliding arc plasma has then proved to be an effective technique during which noticeable improvement in wettability has occurred.

This study demonstrates the feasibility of all-solution-processed mean to fabricate carbon-based non-volatile memory (NVM). The NVM devices were fabricated on polyethylene terephthalate (PET) substrate using spin-coating and spray-coating techniques in the structure of silver nanowires (AgNWs)/graphene oxide (GO)/graphene quantum dots (GQDs)/graphene oxide (GO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/PET. PEDOT:PSS was used as the bottom conductive layer and deposited by spin-coating method. GQDs were used as a charge trapping site in the structure and embedded in the two GO insulator layers. The AgNW metal electrode was formed on top of GO/GQDs/GO/PEDOT:PSS by the spray-coating method. The overall smooth surface morphology of the spray-coated films serves as good contact with the top metal electrode. The electrical characterization of the fabricated device shows the bistable current states with the ON/OFF ratio of 105. The NVM device can be programmed and erased multiple times. Various conduction mechanisms were proposed to describe the charge trapping process in GQD based on the obtained current–voltage measurement.

A GaN metal–insulator–semiconductor high electron mobility transistor (MIS-HEMT) using tri-gate architecture and hybrid ferroelectric charge trap gate stack is demonstrated for normally-off operation. Compared with the conventional planar device, the tri-gate device has the 2-D electron gas (2-DEG) channel exposed on the nanowire sidewalls, so that the trapped charges in the HfON charge-trapping layer can easily deplete the channel from the sidewalls, leading to a high positive threshold voltage ( ${V}_{\text {th}}$ ) to realize the normally-off operation. Moreover, through this electrostatic control on the sidewall, a high density of negative charge caused by hybrid ferroelectric charge trap gate stack with the optimized tri-gate structure, the tri-gate device can achieve normally-off GaN device with both low on-resistance ( ${R}_{ \mathrm{ON}}$ ) and high positive ${V}_{\text {th}}$ . The designed tri-gate device exhibits a high ${V}_{\text {th}}$ of +2.61 V at current density ( ${I}_{\text {DS}}) = 1\,\,\mu \text{A}$ /mm, a high maximum current density ( ${I}_{\text {DS, MAX}}$ ) of 896 mA/mm, a low ${R}_{ \mathrm{ON}}$ of $5.0~\Omega \!\!\cdot \!\!\text {mm}$ and a high breakdown voltage (BV) of 788 V. To the best of our knowledge, the proposed tri-gate device shows the lowest specific on-resistance ( ${R}_{ \mathrm{ON}, \text {SP}}$ ) among reported normally-off GaN device results with BV >650 V.

In the interest of the trend towards miniaturization of electronic gadgets, this study demonstrates a high-density data storage device with a very simple three-stacking layer consisting of only one charge trapping layer. A simple solution-processed technique has been used to fabricate the tristable non-volatile memory. The three-stacking layer was constructed in between two metals to form a two-terminal metal-insulator-metal structure. The fabricated device showed a large multilevel memory hysteresis window with a measured ON/OFF current ratio of 107 that might be attributed to the high charge trapped in molybdenum disulphide (MoS2) flakes-graphene quantum dots (GQDs) heterostructure. Transmission electron microscopy was performed to examine the orientation of MoS2-GQD and mixture dispersion preparation method. The obtained electrical data was used further to speculate the possible transport mechanisms through the fabricated device by a curve fitting technique. Also, endurance cycle and retention tests were performed at room temperature to investigate the stability of the device.

By modulating the thermal stress during film growth, the strained aluminum nitride (AlN) thin films with ferroelectric-like behavior were successfully grown by metal organic chemical vapor phase deposition (MOCVD) on silicon (Si) (111) substrate. The capacitors with strained AlN were fabricated and experimentally demonstrated, the linear to ferroelectric-like behavior on the fabricated AlN capacitors was observed, and the behavior was explained in terms of residual strains in the film. This work reports the ferroelectric-like properties of AlN film grown under specific deposition conditions for the first time.

A high frequency enhancement mode quaternary InAlGaN/GaN MIS-HEMT with recessed gate (Lg = 150 nm) processed using an oxygen-based digital etching technique is presented. The digital etching was performed by cyclic ICP oxygen treatment to oxidize InAlGaN barrier and HCl wet etching to remove the oxidized layer. In this study, we have demonstrated that the threshold voltage can be adjusted in a wide-range from depletion mode to enhancement mode with a nanometer scale gate for high frequency InAlGaN/GaN MIS-HEMT using the digital etching technique. In addition, the etch rate can be controlled from 0.7 nm/cycle to 3.6 nm cycle−1 with RF bias power changing from 0 W to 40 W with high flexibility in etching rate. The post-etching surface roughness was around 0.12 nm regardless of the ICP oxidation voltage. The enhancement-mode InAlGaN quaternary GaN HEMT with maximum drain current of 955 mA mm−1, gm−1 peak of 440 mS mm−1, Vth of 0.2 V, and ft/fmax of 45/59 GHz were achieved using the digital etching for the gate recess structure.

AlGaN/GaN high electron mobility transistors (HEMTs) heterostructures are grown by metal-organic chemical vapor deposition on silicon-on-insulator (SOI) substrate and high-resistivity silicon (HR-Si) simultaneously to investigate the influence of substrate types on electrical and thermal characteristics. The AlGaN/GaN HEMT epitaxial structure grown on SOI achieved high electron mobility (1900 ± 19 cm2 (V s)−1) and high two-dimensional electron gas carrier concentration (9.1 ± 0.1 × 1012 cm−2). The GaN HEMT metal–insulator–semiconductor gate device fabricated on the structure grown on the SOI substrate exhibits higher saturation current and improved buffer breakdown voltage compared with devices fabricated on HR-Si substrate. In particular, SOI substrate helps to improve the thermal-sensitive strain of the GaN-based heterostructure and reduced defect density in the epitaxy, thereby improve the temperature-dependent on-resistance (R ON) and the dynamic R ON of the device.

Colloidal quantum dots (QDs) are promising building blocks towards the development of cost-effective and high-efficiency photoelectrochemical (PEC) cells. Unfortunately, the frequent use of QDs possessing heavy metals (e.g. Cd and Pb) in state-of-the-art QD-based PEC technologies is a major obstacle regarding their future commercial perspective. In this work, we synthesized heavy metal-free quaternary CuZnInS3 (CZIS) with variable Cu : Zn ratios and fabricated corresponding QDs-PEC devices via a facile chemical bath deposition (CBD) technique. It is revealed that the tuned CZIS (1Zn) QDs (i.e. Cu : Zn ratio of 1 : 1) can result in optimized optical properties including enhanced quantum yield, suppressed nonradiative recombination and extended excitonic lifetime. Accordingly, as-fabricated CZIS (1Zn) QD-based photoanodes demonstrated increased charge transfer rate and decreased electron transport resistance for improved PEC performance. The results indicate that tuning the composition of heavy metal-free multinary QDs is one of the promising pathways to achieve eco-friendly and high-performance PEC systems for solar hydrogen production.

We report the improvement in silicon band-edge emission when defects are deliberately introduced in the lattice structures. Silicon is a poor light-emitter due to its indirect bandgap nature. This paper aims to increase the intensity of the light emission from silicon by implantation of boron which will lead to the formation of dislocation loops between the lattice structures. Prior to that, the silicon samples were implanted with high concentration of carbon. Photoluminescence (PL) measurements were carried out to observe the emission in silicon at near infrared region. The temperatures were varied from 10K to 100K to study the effect of temperature towards the peak luminescence intensity. By observing the PL spectra, there are two main peaks that can be seen at ~1112 nm and 1170 nm. Both peaks show significantly higher intensities in the samples incorporated with boron.

Taguchi’s L9 static design was employed to determine the robust design of a zinc oxide (ZnO) nanofilm surface plasmon resonance (SPR) bimetallic sensor. The control factors such as incident wavelength and different thicknesses of silver, gold and ZnO layers were selected. Noise factors include thickness of the chromium layer and the diameter of the biomolecules (i.e. urea) which were simulated using Finite-Difference-Time-Domain (FDTD). Results obtained show that the thickness of the gold layer has a 41.32% dominant factor effect on the minimum reflectance of light $(\mathbf{R}_{\mathbf{min}})$ , whereas the incident wavelength has a 73.15% dominant factor effect on the full-width-at-half-maximum (FWHM) of the SPR signal. The confirmation tests carried out show that the values of $\mathbf{R}_{\mathbf{min}}$ and FWHM were optimized using Taguchi's orthogonal array method leading to a robust design of the SPR sensor.

Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 &deg, C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current&ndash, voltage measurement and UV&ndash, vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 &Omega, cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.