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An improvement of solid-state fluorescence from a luminous nanocomposite made from corn-starch-based bioplastic by adding intentionally Cu-doped carbon quantum dots (CQDs) has been reported. An affordable, environmentally sustainable, one-step hydrothermal technique was employed to synthesize CQDs from Brassica juncea flower extract. The morphological, structural, and physicochemical characteristics of the material were investigated. The quasi-circular shaped CQDs have been found to have a size distribution of 2–5 nm, to have yellow-greenish fluorescence upon UV stimulation, to have excellent photostability, and to be highly water soluble, with a quantum yield of up to 18.4%. Interestingly, the fluorescence spectra of intentionally Cu-doped CQDs (hereafter N, Ca, Cu-doped CQDs) were found to be brighter after 280 nm illumination than unintentional one. Furthermore, as a solid-phase dispersion matrix of CQDs, the environmentally benign and biodegradable bioplastic is appealing. As a result, this work demonstrated the effect of Cu-doping on solid-state fluorescence in the down-conversion of UVC tubes via a composite constructed by inserting CQDs into the solid-state matrix of corn-starch-based bioplastic nanocomposite, which demonstrated vivid greenish-yellow emission in the electroluminescent spectra with CIE chromatic coordinates (0.33, 0.58 vs. 0.31, 0.67). [ABSTRACT FROM AUTHOR]

The biomemristor has gained considerable attention because of its exceptional scalability, remarkable flexibility, simplicity of processing, and low manufacturing cost. Natural biomaterial-based memristors have been demonstrated for prospective application due to their sustainability, non-toxicity, environmental friendliness, degradability, and biocompatibility. Hence, the leaf extract of the traditional medicinal tree neem (Azadirachta indica) was employed in this study to efficiently synthesize a biomaterials-inspired thin film for biomemristor applications. Various morphological, compositional, structural, surface functional, optical, and thermogravimetric analyses were performed on neem thin film. Satisfactory bipolar, reversible and repeatable resistive switching characteristics were obtained. Furthermore, phototunable resistive switching behaviours were examined by embedding carbon quantum dots (CQDs) with neem to develop a CQDs@neem composite biomemristor, which resulted in a 16% reduction in SET voltage and a 2.6% rise in RESET voltage. Satisfactory memristive behaviour was achieved, including appropriate endurance, retention, and a stable resistance ratio between high and low resistance states. The underlying current conduction mechanisms were explored. Finally, a method involving the formation/annihilation of an Ag metal filament and an ionized molecular vacancy filament is proposed to explain the resistive switching behaviour of CQDs@neem composite memristors. [ABSTRACT FROM AUTHOR]

Implementing biocompatible and biodegradable information storage would be a giant leap toward next-generation green electronics. Natural biomaterial-based memristors, with their proven prospective applications due to their sustainable, non-toxic, eco-friendly, degradable, and biocompatible characteristics, will not only save our environment from harmful chemicals and e-wastes while also allowing the electronic industry to grow. In this work, a biomaterials-inspired thin film was successfully created from the leaf extract of the traditional medicinal herb giloy (Tinospora cordifolia) for biomemristor applications. The electronic-grade giloy thin film spin coated on FTO/glass using aqueous giloy solution exhibits remarkable transparency over the majority of the visible spectral range. A reasonable bipolar reversible and non-volatile resistive switching behaviour was obtained. In addition, incorporating carbon quantum dots (CQDs) with giloy to generate a CQDs@giloy composite film resulted in phototunable resistive switching characteristics with a 16% decrease in SET voltage. A reasonable memristive behaviour such as proper endurance, retention and a steady resistance ratio between high and low resistance states over 100 consecutive switching cycles and 100 flexing cycles was obtained. The conduction mechanisms were analysed. Finally, a mechanism in combination with the formation/annihilation of an Ag metal filament and ionized molecular vacancy filament is proposed to explain the resistive switching behaviour. [ABSTRACT FROM AUTHOR]

The use of naturally produced biomaterials to develop various electronic devices addresses the long-term demand for bioelectronics. Natural biomaterial-based memristors have been proven for potential applications due to their sustainability, non-toxicity, ecological friendly, degradability, and biocompatibility. Hence, in this study, a biomaterials-inspired thin film was successfully synthesized from the leaf extract of the traditional medicinal tree, neem (Azadirachta indica) for prospective biomemristor applications that had not before been investigated. The electronic-grade thin film of neem exhibits up to 75% transparency over the majority of the visible spectrum. The various physiochemical, morphological, chemical and topographic characteristics of the deposited neem thin film have been investigated by XRD, FESEM, EDX, AFM and FTIR. Thermal stability of the neem film was further examined through thermogravimetric analysis. The fabricated FTO/Neem/Ag biomemristor demonstrated a reasonable bipolar, repeatable and non-volatile resistive switching along with a low yet stable resistance ratio between high and low resistance states, as well as acceptable endurance and retention characteristics. Using cyclic voltammetry, the physicochemical aspects were investigated further, and the underlying plausible memristive switching mechanisms were discussed. In addition, a feasible conduction mechanism is provided. Neem was also probed to demonstrate its transitory nature as an economical and eco-friendly non-volatile memory device. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the thermal conductivity of lightly Sr- and Zn-doped La2CuO4 high temperature superconductor cuprates has been analyzed auspiciously. We used a quantum dynamical technique to develop the symbol of relaxation time and other scattering processes from frequency (energy) line widths in this formulation. The primary focus of this study is the effect of phonon-dopant atom scattering on the thermal conductivity of doped La2CuO4, as well as other dominant scattering mechanisms such as electron–phonon, cubic and quartic anharmonic phonon, cubic and quartic phonon interference, and phonon-magnon, among others. An acceptable level of agreement between theory and experiment has been reached. [ABSTRACT FROM AUTHOR]

The thermal conductivity of high temperature superconductor cuprates (Zn-doped yttrium barium copper oxide (YBCO), YBa2(Cu1−xZnx)3O7−δ) is successfully analyzed in the temperature range of 0–200 K. Despite the fact that several theories have been offered to assess the thermal conductivity of high temperature superconductors since the pioneering work of Bardeen, Rickayzen, and Tewordt until now, a satisfactory solution has yet to be found. The idea of relaxation time and various scattering mechanisms has been developed from frequency line widths using a quantum dynamical approach in this current formulation. The influence of phonon–dopant atom scattering on the thermal conductivity of Zn-doped YBCO has been investigated in this study. This proposed theory has been able to achieve successful agreement between theory and experiment. [ABSTRACT FROM AUTHOR]

Single-electron transistors (SETs), which operate by quantum-mechanically controlled coulomb blockade and the single-electron tunneling effect, are promising candidate future nanoelectronic devices. A physics-based analytical model is developed to study the current and quantum capacitance of a SET with an island made of monolayer tungsten diselenide (WSe2) nanoribbon in an armchair pattern. It is noteworthy that the SET current is not degraded much in the coulomb blockade region, whereas outside this region, the SET current decreases with varying width of the nanoribbon, presumably due to the greater width of the potential well in the island that lowers the tunneling rate. Since atomically thin nanoribbon possesses quantum capacitance, which might cause further degradation in the SET performance, its influences are also studied. A three-band nearest-neighbor tight-binding model is applied to assimilate the details and information of the energy band formation into the quantum capacitance estimation. [ABSTRACT FROM AUTHOR]

ZnO nanomaterials are synthesized using one-pot synthesis method. Equimolar solution of Zinc Nitrate hexahydrate (Zn(NO3)2.6H2O) and Hexamethylenetetramine (C6H12N4) is used as a precursor for ZnO formation. Different nanostructures of ZnO are achieved by controlling the pH of the growth solution in the range 2–12 (acidic to alkali). ZnO nanostructures are evaluated for hydrophobic property using static contact angle measurement setup and UV photosensing activity. Surface morphology, structural properties and compositional analysis of ZnO nanostructures are examined by field emission scanning electron microscope (FE-SEM), energy dispersive X-ray analysis (EDX), high-resolution transmission electron microscope (FEG-TEM) and X-ray diffraction (XRD) measurements. Existence of ZnO wurtzite structure is confirmed from XRD study and is analyzed by Rietveld refinement method. Nanomaterials are characterized using Raman spectroscopy which confirms highest oxygen deficiency in ZnO nanorods. The material shows remarkable superhydrophobic and UV photosensing property and hence the name multifunctional. Among all morphologies grown at different pH values, ZnO nanorods show superhydrophobic nature with contact angle more than 170°. Total surface energy value of ZnO nanostructures is calculated using Wendt two-component theory. Different ZnO nanostructures (with variation of pH value) are used to study UV photosensing property. Responsivity and photocurrent show a strong dependence on the morphology of ZnO. [ABSTRACT FROM AUTHOR]

A critical analysis of charge carrier statistics influenced by quantum capacitance is carried out in order to predict the electrical performance of a nanoscale metal–oxide–semiconductor field-effect transistor (MOSFET) with a channel made of a monolayer tungsten diselenide (WSe2) two-dimensional (2D) crystal semiconductor. Since quantum capacitance originating from two-dimensional electron gas in a quantum well or an inversion layer does not completely screen the quasistatic electric field during applied gate voltage, the partial penetration of an external electric field through the 2D semiconductor channel will generate excess charge carriers; thus quantum capacitance will play an important role in determining the overall charge carrier density in the channel. Therefore, common methods used to extract charge carrier density in the channel for three-dimensional (3D) crystal semiconductors will yield inaccurate results when used for 2D crystal semiconductors. To address this issue, this study proposes a modified approach for extracting charge carrier density in WSe2-based 2D semiconductors by combining the appropriate carrier statistics with consideration of quantum capacitance. In addition, the study investigates the effect of interface traps on overall capacitance, which may influence the electrical performance of a nanoscale MOSFET with monolayer WSe2 as a channel material. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon substrates have been investigated. ZnO/Si substrates are characterized by Rutherford backscattering (RBS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). ZrO2 thin films have been deposited on ZnO using microwave plasma enhanced chemical vapour deposition at a low temperature (150°C). Using metal insulator semiconductor (MIS) capacitor structures, the reliability and the leakage current characteristics of ZrO2 films have been studied both at room and high temperatures. Schottky conduction mechanism is found to dominate the current conduction at a high temperature. Good electrical and reliability properties suggest the suitability of deposited ZrO2 thin films as an alternative as gate dielectric on ZnO/n-Si heterostructure for future device applications. [ABSTRACT FROM AUTHOR]

We report on the counter intuitive reversible crystallisation of two-dimensional monolayer of Trisilanolisobutyl Polyhedral Oligomeric SilSesquioxane (TBPOSS) on water surface using synchrotron x-ray scattering measurements. Amphiphilic TBPOSS form rugged monolayers and Grazing Incidence X-ray Scattering (GIXS) measurements reveal that the in-plane inter-particle correlation peaks, characteristic of two-dimensional system, observed before transition is replaced by intense localized spots after transition. The measured x-ray scattering data of the non-equilibrium crystalline phase on the air-water interface could be explained with a model that assumes periodic stacking of the TBPOSS dimers. These crystalline stacking relaxes upon decompression and the TBPOSS layer retains its initial monolayer state. The existence of these crystals in compressed phase is confirmed by atomic force microscopy measurements by lifting the materials on a solid substrate. [ABSTRACT FROM AUTHOR]