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The quantum Toffoli gate is one of the essential reversible universal logic gates widely used for optical data processing. Herein, a new scheme of developing all‐optical Toffoli gate using a two‐dimensional silicon–air photonic crystal is proposed. For the realization of the Toffoli gate, the principles of constructive and destructive interference of light are used. The Toffoli gate comprises two‐input–three‐output‐based optical AND gate, and a two‐input–one‐output optical XOR gate. Two Y junction power splitters have been used at the two inputs of the AND gate. The operating wavelength of the proposed Toffoli gate is 1550 nm along with the wafer size of 50 µm × 50 µm. The performance of the Toffoli gate has been analysed and simulated by the plane‐wave expansion method and finite‐difference time‐domain method. The response time and contrast ratios are also obtained from the simulation. The proposed Toffoli gate is intensity encoded with no non‐linear material within the crystal which shows significant improvement over other proposals. [ABSTRACT FROM AUTHOR]

Vertically well aligned ZnO nanorods (NRs) were grown on Si(100) substrate using RF magnetron sputtering technique. Scanning electron microscopy images confirms uniform distribution of NRs on 2 in. wafer with average diameter, height and density being ~75 nm, ~850 nm, and ~1.5 × 1010 cm-2, respectively. X-ray diffraction reveals that the ZnO NRs are grown along c-axis direction with wurtzite crystal structure. Cathodoluminescence spectroscopy, which shows a single strong peak around 3.24 eV with full width half maxima 130 meV, indicates the high crystalline and optical quality of ZnO and very low defect density. Vertically aligned nanosensors were fabricated by depositing gold circular Schottky contacts on ZnO NRs. Resistance responses of nanosensors were observed in the range from 50 to 150 °C in 1% and 5% hydrogen in argon environment, which is below and above the explosive limit (4%) of hydrogen in air. The nanosensor's sensitivity increases from 11% to 67% with temperature from 50 to 150 °C and also shows fast response time (9-16 s) and moderate recovery time (100-200 s). A sensing mechanism is proposed based on Schottky barrier changes at heterojunctions and change in depletion region of NRs. [ABSTRACT FROM AUTHOR]

• All optical 3-qubit Fredkin gate with Photonic Band gap Crystal. • A small structure is used for the proposed system of dimension 60 µm × 75 µm wafer. • This structure has a response time of 3.5 ps. • All-optical combinational/ sequential systems can be realized from the implemented system. The authors demonstrate an all-optical Fredkin gate which implements an interference based controlled swap operation. This realization has a small footprint (60 µm × 75 µm wafer size), and in this scheme, the phase shifts are achieved by the variation of the path length of the light necessary for the operation. For the simulation, the wavelength used is 1550 nm. This reversible logic gate optimizes the power requirement and have a non-dissipative operation. PWE and FDTD methods are used for the simulation process. The novelty of the proposed research work is that the implementation of the Fredkin gate is organized only by the constructive/destructive interferences of the light. No nonlinear switching is used to do it and hence the speed of operation goes faster than most of the the Fredkin gates in PhCs using non linearities and it proposes a very good contrast ratio. [ABSTRACT FROM AUTHOR]

Self-aligned ZnO nanorods (NRs) were grown on n-Si(100) substrate by RF sputtering techniques. The NRs are uniformly grown on 2-inch wafer along [0001] direction. Single-crystalline wurtzite structure of ZnO NRs was confirmed by X-ray diffraction. The average diameter, height, and density of NRs are found 48 nm, 750 nm, and 1.26×1010 cm–2, respectively. The current-voltages (I-V) characteristics of ZnO NRs/Si heterojunction (HJ) were studied in the temperature range of 120–300K and it shows a rectifying behavior. Barrier height (ϕB) and ideality factor (η) were estimated from thermionic emission model and found to be highly temperature dependent in nature. Richardson constant (A*) was evaluated using Richardson plot of ln(Io/T2) versus q/kT plot by linear fitting in two temperature range 120–180K and 210–300 K. Large deviation in Richardson constant from its theoretical value of n-Si indicates the presence of barrier inhomogeneities at HJ. Double Gaussian distribution of barrier height with thermionic equation gives mean barrier heights of 0.55±0.01 eV and 0.86±0.02 eV for two different temperature regions 120–180K and 210–300 K, respectively. Modified Richardson plot provided two values of Richardson constant for two temperature regions. However, for higher temperature range (210–300 K), the calculated value of Richardson constant ~123 A cm–2 K–2 was close to the ideal Richardson constant for n-Si. [ABSTRACT FROM AUTHOR]

We demonstrate RF sputtered Ni-doped ZnO nanostructures for detection of extremely low concentration (1 ppm) of hydrogen gas at moderate operating temperature of 75 °C. Structural, morphological, electrical and hydrogen sensing behavior of the Ni-doped ZnO nanostructures strongly depends on doping concentration. Ni doping exceptionally enhances the sensing response and reduces the operating temperature of the sensor as compared to undoped ZnO. The major role of the Ni-doping is to create more active sites for chemisorbed oxygen on the surface of sensor and, correspondingly, to improve the sensing response. The 4 at% of Ni-doped ZnO exhibits the highest response (∼69%) for 1% H 2 at 150 °C, which are ∼1.5 times higher than for the undoped ZnO. This is ascribed to lowest activation energy ∼6.47 KJ/mol. Diminishing of the relative response was observed in 6% Ni- doped ZnO due to separation of NiO phase. [ABSTRACT FROM AUTHOR]

• All-optical integrated Pauli X, Y and Z gate system is proposed. • The system implemented with a photonic bandgap crystal made of Si-air configuration. • The implementation is a linear system operating at 1550 nm wavelength. • Response time is 2 ps, contrast ratio of 10.4 dB and bit rate of 0.25 Tbps. • The smaller footprint of 70 µm × 70 µm. • The proposed device can help build a photonic chip in the nanodomain. Nano-scale all-optical logic gates systems are desirable for the all-optical computing and signal processing applications. All-optical Quantum computing offers excellent computational abilities and lossless operations. The Pauli X, Y and Z gates are vital quantum logic gates for all-optical systems. In this paper, the integrated all-optical Pauli X, Y, Z gate is realized using a square lattice 2D photonic crystal of silicon rods. The phase encoding and intensity encoding techniques have been used simultaneously for the integrated operation. Pauli X, Y, Z logic gate truth table has been verified at the operating wavelength of 1.55 µm.The system offers a linear operation, compact size, low power requirement, and high contrast ratio of 10.4 dB. The footprint of the proposed structure is about 70µm x 70µm and demonstrates a fast response time of 2 ps, bit rate of 0.25 Tbps, which makes it suitable for photonic integrated circuits (PICs). [ABSTRACT FROM AUTHOR]

ZnO thick Stress relaxed films were deposited by reactive magnetron sputtering on 2"-wafer of SiO2/Si at room temperature. The residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 109 × 11.28 x 109 dyne/cm2 with compressive in nature. Sputter pressure changes the deposition rates, which strongly affects the residual stress and surface morphologies of ZnO films. The crystalline wurtzite structure of ZnO films were confirmed by X-ray diffraction and a shift in (0002) diffraction peak of ZnO towards lower 2θ angle was observed with increasing the compressive stress in the films. The band gap of ZnO films shows a red shift from ~3.275 eV to ~3.23 eV as compressive stress is increased, unlike the stress for III-nitride materials. A relationship between stress and band gap of ZnO was derived and proposed. The stress-free growth of piezoelectric films is very important for functional devices applications. [ABSTRACT FROM AUTHOR]

Uniformly distributed and defect-free vertically aligned ZnO nanorods (NRs) with high aspect ratio are deposited on Si by sputtering technique. X-ray diffraction along with transmission electron microscopy studies confirmed the single crystalline wurtzite structure of ZnO. Absence of wide band emission in photoluminescence spectra showed defect-free growth of ZnO NRs which was further conformed by diamagnetic behavior of the NRs. H2 sensing mechanism based on the change in physical dimension of channel is proposed to explain the fast response (~21.6 s) and recovery times (~27 s) of ZnO NRs/Si/ZnO NRs sensors. Proposed H2 sensor operates at low temperature (~70°C) unlike the existing high temperature (>150°C) sensors. [ABSTRACT FROM AUTHOR]

In the present work, ZnO nanorods and Ag nanoparticles (NPs) decorated ZnO nanorods (NRs) were synthesized on a Si/SiO2 substrate by a simple chemical hydrothermal route. Various characterization techniques studied phase formation, surface morphology, and elemental composition of prepared samples. Gas sensing measurements for pristine ZnO and Ag/ZnO NRs have been carried out under a low detection limit (2–10 ppm). The highly crystalline nature of NRs aided in achieving a great sensing response. The ZnO NRs exhibit a sensing response of 934% towards 10 ppm NO2 at a working temperature of 180 °C. However, Ag/ZnO sensor gives the highest sensing response of 1075% for 10 ppm NO2 at a working temperature of 180 °C. The cause behind the increment of Ag/ZnO sensor response is explained via chemical and electronic models. These observations make an energy-efficient sensor for the detection of NO2 in the environment. [ABSTRACT FROM AUTHOR]

A fractal shaped metasurface inspired graphene-based absorber is proposed in this paper for THz range application. The space-filling property of the Haferman carpet pattern is utilized to realize the shape of the graphene layer deposited on a dielectric layer with a metallic ground that is found to exhibit improved absorbance compared to the Euclidean​ shaped absorber counterparts. The resonating structure is made up of a graphene layer based on a second iteration Haferman Carpet fractal geometry that constitutes the unit cell of the metasurface. The absorbance is polarization independent for normal incidence. The efficacy of the absorber has been studied for various chemical potentials that render the tunability. Comprehensive discussions on the obtained results are presented by using numerical simulation to determine the electric field distributions and the absorption spectra. Over 90% absorbance is observed for the frequency range of 7.66 THz to 9.025 THz, resulting in a bandwidth of 1.365 THz. Therefore, these graphene-based Haferman carpet fractal shaped THz absorbers can be vastly used in high-performance THz devices, electro-optical switches and bio-sensors. • Fractal patterned broadband absorbers in the emerging 6G communication frequencies. • Works with more than 90% absorption over the frequency range 7.66 THz to 9.0 25 THz. • Absorber is polarization independent for different chemical potential of graphene. • TE and TM mode absorbance nearly same till 50-degree of incidence angles. [ABSTRACT FROM AUTHOR]

Ba0.5Sr0.5TiO_3 (BST) thin films were deposited on sapphire substrate by RF magnetron sputtering techniques and interdigital capacitor (IDC) structures were fabricated using photolithography. Gamma irradiation induced changes of the BST based tunable capacitor have been investigated under various doses from 0 kGy to 600 kGy. Structural and surface morphological studies have been carried out for un-irradiated and irradiated film and revealed that the grain sizes and crystallinity are strongly depended on gamma irradiation doses. The leakage current is increased with increasing gamma irradiation doses due to creation of charge carriers and large numbers of defect in close proximity, provided path for charge carriers. The capacitance of the IDC devices decreased with increasing gamma dose up to 50 kGy and thereafter capacitance gradually increased with radiation doses and reached higher than the un-irradiated device at 600 kGy for 1 MHz frequency. The observed tunability (\sim 25\% ) of the un-irradiated device was found nearly constant with gamma irradiation doses. This study shows that gamma ray induced defects play important role to the electrical properties of the devices and the BST based devices are highly resistant to gamma radiation, which reflects possible use in space and nuclear applications. [ABSTRACT FROM AUTHOR]

• A biodegradable, flexible substrate based on Chitosan/PVP was synthesized. • Cost-effective and easily to process. • Substrate is highly transparent, thermally and mechanically stable. • It will be used as disposable substrate for gas sensing applicaion. In the present work, biodegradable and flexible chitosan/polyvinylpyrrolidone (CHP) polymeric substrate was fabricated by solvent casting method. This is a novel demonstration of the combination of natural polymer (chitosan) and synthetic polymer (PVP) for next-generation semiconductor device applications. The ZnO thin films were successfully synthesized on these polymeric substrates by facile drop-casting method for gas sensing applications. The hydrogen gas sensing properties of ZnO deposited on the polymeric substrate and SiO 2 substrate show similar performance. The structural, morphological, optical, thermal, and tensile strength of the CHP substrate were studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV-visible spectroscopy, Derivative thermogravimetric analysis (DTG), and Universal testing machine (UTM), respectively. Our study suggests that the biodegradable CH/PVP flexible polymeric substrate provides a new way for the implementation of an eco-friendly green substrate in numerous electronic device applications. [ABSTRACT FROM AUTHOR]