Single-layer Thin Films Research Articles

Graphene Applications in Sensors: Performance Optimization and Prospects

A sensor, as a detection device, is able to receive information and convert it into an electrical signal or other form of signal for output. In today's era of rapid development of intelligence, digitalization and networking, sensors have become the core tool for obtaining information. As technology advances, higher standards have been set for sensor sensitivity and application breadth. Graphene, a single-layer thin film material composed of carbon atoms arranged in a hexagonal honeycomb, has attracted much attention in the engineering industry because of its unique structure and its excellent electrical and mechanical properties. Among the many potential applications, sensors are seen as one of the most promising application areas for graphene.In this paper, the basic structural characteristics and unique properties of graphene are first outlined, and then the specific application cases in many fields such as biomedical sensors, flexible pressure sensors and photoelectric chemical sensors are discussed in detail, and the wide use of graphene materials is demonstrated by examples. At the same time, the different preparation methods of graphene are compared and analyzed, and the challenges faced by graphene sensors in the commercialization process are pointed out. Finally, a series of suggestions and prospects are put forward for the future development path of graphene sensors.

A High-Sensitivity Fiber Optic Soil Moisture Sensor Based on D-Shaped Fiber and Tin Oxide Thin Film Coatings.

We present a high-sensitivity fiber optic soil moisture sensor based on side-polished multimode fibers and lossy mode resonance (LMR). The multimode fibers (MMFs), after side-polishing to form a D-shaped structure, are coated with a single-layer SnO2 thin film by electron beam evaporation with ion-assisted deposition technology. The LMR effect can be obtained when the refractive index of the thin film is positive and greater than its extinction coefficient and the real part of the external medium permittivity. The D-shaped fiber optic soil moisture sensor was placed in soil, allowing moisture to penetrate into the thin film microstructure, and it observed the resonance wavelength shift in LMR spectra to measure the relative humidity change in soil. Meanwhile, an Arduino electronic soil moisture sensing module was used as the experimental control group, with soil relative humidity ranging from 10%RH to 90%RH. We found that the D-shaped fiber with a residual thickness of 93 μm and SnO2 thin film thickness of 450 nm had a maximum sensitivity of 2.29 nm/%RH, with relative humidity varying from 10%RH to 90%RH. The D-shaped fiber also demonstrates a fast response time and good reproducibility.

A Flexible Organomagnetic Single-Layer Composite Film with Built-In Multistimuli Responsivity.

Materials possessing multiple properties and functionalities, that can be controlled or modulated by external stimuli, are a central focus of current research in materials sciences due to their potential to significantly enhance various future technological applications. Herein, we report a significant advancement in this field through the development of a smart, multifunctional organomagnetic composite material. By utilizing a thin layer of polydimethylsiloxane (PDMS) and polypyrrole (PPy) precursors, doped with nickel nanoparticles (NiNPs), we have created an innovative organomagnetic, PDMS/PPy/NiNPs (PPN), single-layer composite film that displays multistimuli responsivity. The study presents the first demonstration of a multifunctional flexible, three-component film structure integrating the structural and flexible PDMS component, together with a conductive polymer component and metal-based nanoparticles into a single-layer design, which displays enhanced and unprecedented responsivity properties against multiple different stimuli. Unlike typical stacked multilayered structures, that exhibit one or two functionalities at most, this novel configuration exhibits multiple functionalities, including magnetoresistance, mechanical stress response, piezoresistivity, and temperature change sensitivity. The as-prepared film demonstrates notable magnetoresistance responsivity, with a relative electrical resistance, ΔR/R0, changing under a weak magnetic field and under ambient conditions. The significance of our study lies in the film's versatility, stability, and sensitivity, especially within the physiological temperature range, making it highly relevant for future biomedical applications. Furthemore, the film's sensitivity to mechanical deformation reveals an impressive piezoresistance behavior. Unlike existing multilayer architectures of higher complexity, our single-layer thin film offers a simpler, more flexible, and reliable solution with a broad range of stimuli-sensing capabilities. The significance of this novel multiresponsive composite material is underscored by the growing demand for advanced materials in biomedical devices, magnetic switches, sensors, electronic skin, transistors, and organic spintronic devices. These promising organomagnetic self-standing layers provide a robust platform for future technological innovations.

Advancing X‐Band Electromagnetic Interference Shielding: Single‐Layer Thin Films of Fe3O4‐MWCNT (1:2)‐PVDF Meta‐Nanocomposite Fabricated by Low‐Cost Drop‐Casting Process

This study, investigate of ternary thermoplastic fluoropolymer blend nanocomposite (NC) system for improved microwave (MW) shielding, consisting of polyvinyl dimethylamine fluoride (PVDF) and Fe3O4‐multiwalled carbon nanotube (MWCNT) (1:2) NC. Using a hydrothermal process, complex hierarchical nanostructures (NSs) of Fe3O4‐MWCNT (1:2) NC are produced. These NSs are then integrated using a drop‐casting technique into PVDF matrices with different wt% (20, 40, and 60 wt%) and thicknesses (20, 50, and 80 μm). The single‐layer thin films (SLFs) with the Fe3O4‐MWCNT (1:2)‐PVDF matrix are successfully produced as a consequence of this approach. The presence of FeOC bonding from X‐ray photoelectron spectroscopy (XPS) analysis confirms chemical interaction, while scanning electron microscopy (SEM–Energy dispersive spectroscopy EDX) imaging analysis for material homogeneity. Moreover, the SLFs of Fe3O4‐MWCNT (1:2)‐PVDF (20, 40, and 60 wt% for 80 μm thickness) are newly discovered meta‐nanocomposites (MNCs) properties, which are evidenced by negativeMW real complex permittivity (−274.4, −271.2, and −136.4), superior attenuation constant (12862.73, 16265.18, and 12256.34), and higher alternating current (AC)electrical conductivities (1020.8, 1174.6, and 727.7 S m−1). The synergistic impact of higher attenuation and AC conductivity of MNCs results in an increased average MW shielding effectiveness of ≈33.28 dB for Fe3O4‐MWCNT (1:2)‐PVDF 20 wt% MNCs (≈80 μm).

Stabilization and control of weakly correlated polar skyrmions in ferroelectric thin films

In recent years, polar topological textures like skyrmions and vortices in ferroelectric superlattices and multilayers have received extensive attention. However, the polar topological textures in these systems suffer strong interactions and are difficult to be manipulated as individual elements, limiting their application prospects in storage and logic devices. Here, via phase field simulations, we demonstrate domain engineering as a feasible strategy to create diverse weakly correlated polar topological texture arrays in single-layer tetragonal ferroelectric thin films, including Néel-type skyrmions with positive/negative topological charges and Bloch-type skyrmions with different chirality. We calculate the stability phase diagram and reveal the evolution characteristics of these polar topological textures under local electric and mechanical stimuli. We realize local erasing and writing of single Néel- and Bloch-type skyrmions, as well as deterministic chirality control of single Bloch-type skyrmion, confirming the weak correlation of the polar skyrmions. Our study therefore demonstrates domain engineering as an effective strategy for stabilizing weakly correlated polar topological textures, which extends the existence system of polar topological textures and paves a new way for the design of storage and logic devices based on polar topological textures.

Comparative Study of Plasma-Enhanced-Atomic-Layer-Deposited Al2O3/HfO2/SiO2 and HfO2/Al2O3/SiO2 Trilayers for Ultraviolet Laser Applications.

High-performance thin films combining large optical bandgap Al2O3 and high refractive index HfO2 are excellent components for constructing the next generation of laser systems with enhanced output power. However, the growth of low-defect plasma-enhanced-atomic-layer-deposited (PEALD) Al2O3 for high-power laser applications and its combination with HfO2 and SiO2 materials commonly used in high-power laser thin films still face challenges, such as how to minimize defects, especially interface defects. In this work, substrate-layer interface defects in Al2O3 single-layer thin films, layer-layer interface defects in Al2O3-based bilayer and trilayer thin films, and their effects on the laser-induced damage threshold (LIDT) were investigated via capacitance-voltage (C-V) measurements. The experimental results show that by optimizing the deposition parameters, specifically the deposition temperature, precursor exposure time, and plasma oxygen exposure time, Al2O3 thin films with low defect density and high LIDT can be obtained. Two trilayer anti-reflection (AR) thin film structures, Al2O3/HfO2/SiO2 and HfO2/Al2O3/SiO2, were then prepared and compared. The trilayer AR thin film with Al2O3/HfO2/SiO2 structure exhibits a lower interface defect density, better interface bonding performance, and an increase in LIDT by approximately 2.8 times. We believe these results provide guidance for the control of interface defects and the design of thin film structures and will benefit many thin film optics for laser applications.

High-temperature superconductor quantum flux parametron for energy efficient logic

We report the fabrication and measurement of quantum flux parametron logic from high-transition-temperature Josephson junctions operating at 25 K, above the temperature of liquid helium. The circuits are written directly into the plane of a single-layer thin film of YBa2Cu3O7 using a focused helium ion beam. A single-cell quantum flux parametron was constructed and correct logic operation was verified by using an on-chip superconducting quantum interference device for readout. A three-cell shift register was also fabricated and tested using a three-phase clock cycle. We estimate the average bit energy to be about 1×10−20 J at 1 GHz.

Segmented Control of Selenization Environment for High-Quality Cu2ZnSn(S,Se)4 Films Toward Efficient Kesterite Solar Cells.

High-crystalline-quality absorbers with fewer defects are crucial for further improvement of open-circuit voltage (VOC) and efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. However, the preparation of high-quality CZTSSe absorbers remains challenging due to the uncontrollability of the selenization reaction and the complexity of the required selenization environment for film growth. Herein, a novel segmented control strategy for the selenization environment, specifically targeting the evaporation area of Se, to regulate the selenization reactions and improve the absorber quality is proposed. The large evaporation area of Se in the initial stage of the selenization provides a great evaporation and diffusion flux for Se, which facilitates rapid phase transition reactions and enables the attainment of a single-layer thin film. The reduced evaporation area of Se in the later stage creates a soft-selenization environment for grain growth, effectively suppressing the loss of Sn and promoting element homogenization. Consequently, the mitigation of Sn-related deep-level defects on the surface and in the bulk induced by element imbalance is simultaneously achieved. This leads to a significant improvement in nonradiative recombination suppression and carrier collection enhancement, thereby enhancing the VOC. As a result, the CZTSSe device delivers an impressive efficiency of 13.77% with a low VOC deficit.

Deposition and nanoindentation study of a novel TiNi/Ag bi-layer shape memory film

Compositions, surface morphologies and mechanical properties of a novel designed TiNi/Ag bi-layer film grown by DC magnetron sputtering at various processes have been investigated. Ar pressure and sputtering power had significant effects on quality and composition of TiNi/Ag bi-layer films. The TiNi/Ag bi-layer film processed by sputtering under high Ar pressure (0.36 Pa) was porous, while better density films can only be obtained at low pressure (0.12 Pa). The composition of TiNi/Ag bi-layer films can be adjusted by sputtering power. The load-displacement curves show the multiple “pop-ins”along nanoindentation loading, as indentation depth does not exceed the pure Ag film thickness (∼340 nm). At the maximum loading of 140 mN, martensitic transformation induced by nanoindentation in TiNi/Ag bi-layer films was not found, and depth recovery ratio was 39%. Moreover, based on the load displacement curve analysis, the hardness and elastic modulus values of TiNi/Ag bi-layer films were 4 ± 0.2 Gpa and 79 ± 2 Gpa, respectively. Comparing with martensitic phase of single-layer TiNi thin films at room temperature, the coexistence of parent phase and martensitic phase of TiNi/Ag bi-layer films were mainly due to strong confinement effect of Ag layer deposition on TiNi thin film. The residual stress calculated by using conventional sin2ψ method was around −0.458 GPa. The present study provided an important theoretical basis for the preparation of TiNi/Ag bi-layer film with higher quality and performance.

Enhanced field emission characteristics of WS2 nano-films by diamond film and Mo film

WS2 is a type of transition metal chalcogenide materials (TMDCs) that exhibits exceptional photoelectric properties. Due to its atomically sharp edges, WS2 has the capability to enhance the electric field around its edges, thus presenting significant potential in field emission applications. In this study, the electron beam vapor deposition (EBVD) system and microwave plasma chemical vapor deposition (MPCVD) system were used to prepare a series of single-layer WS2 films，single-layer diamond films and diamond/WS2 nano-composite films on N-type highly doped Si substrate, and Mo/WS2 nano-composite films were prepared on Al2O3 ceramic substrate. Based on the characterization and analysis of the microstructure and chemical composition of each thin film layer in the above film devices, the field emission (FE) characteristics of each thin film device are compared and studied. The results demonstrate that the maximum FE current density of diamond/WS2 nano-composite film device is 912 μA/cm2, which is 2.7 times of the maximum FE current density of Mo/WS2 nano-composite film device 330 μA/cm2, and 3.4 times of the maximum FE current density of the single-layer diamond thin film device 267 μA/cm2. The single layer WS2 film did not exhibit measurable FE performance. The working principles of thin film field emission devices with various structures are introduced. It is considered that the diamond layer plays the role of electron accelerating layer, which not only effectively improves the FE characteristics of diamond/WS2 nanocomposite film, but also improves the repeatability and long-term stability of diamond/WS2 nanocomposite film FE devices.

Sol-Gel Spin Coated Transparent Single-TiO2 and SiO2 Thin Film on Glass for Opto-electronic Applications

Great attention has been given on the sol-gel synthesis and spin-coating deposition techniques for the fabrication of various thin films. Because of its simple technique to fabricate dielectric (metal oxide) films using tetraethyl orthosilicate and titanium isopropoxide precursors. In this work, transparent single layer of SiO2 and TiO2 thin film was deposited on a glass substrate and characterized by FTIR, UV-visible spectroscopy, fluorescence and scanning electron microscopy techniques. The single layer thin film was mechanically stable and strong by adhering to glass substrates. The FTIR transmittance spectrum evidenced the existence of Si-O-Si and Ti-O-Ti at ~1100 and 1400 cm-1. The UV-visible absorbance spectra of single layer of SiO2 and TiO2 thin films showed strong absorption at below 00 nm. The excitation wavelength at 380 nm, the fluorescence spectra of both thin films showed the highest emission spectrum in between 733-798 nm. The SEM studies confirmed the smooth surface in both SiO2 and TiO2 layers. Further, it could be useful for various applications such as back reflector in solar cells, anti-reflection coatings, hydrophobic and anti-fogging materials.

The first proof-of-concept of straightforward and ambient-processed CsPbBr3 perovskite light-emitting electrochemical cell

All-inorganic cesium lead-halide perovskite thin films show great promise for optoelectronic applications. This study introduces a novel synthesis strategy for CsPbBr3 thin films, conducted on a preheated substrate. The synthesis process involves precise control and optimization of parameters under ambient conditions, eliminating the need for a glovebox. Therefore, a facile and low-cost way to fabricate CsPbBr3 perovskite thin films for potential optoelectronic applications has been provided by this method. The effects of various parameters, such as precursor concentration, annealing temperature, and polyethylene oxide (PEO) addition, on the structure, morphology, and optical properties of the perovskite films were systematically studied. The optimal conditions for the highest photoluminance and maximum surface coverage were found to be 0.26 M precursor concentration, 100 °C annealing temperature, and 100:65 CsPbBr3:PEO weight ratio. Uniform and bright perovskite films with over 99% surface coverage, reduced grain size, and suppressed trap density were obtained as a result of these conditions. The PL intensity of the optimized composite thin film exhibited a minor decrease of 6% from its initial value over six months in an ambient environment. A proof-of-concept perovskite light-emitting electrochemical cell (PeLEC) was constructed utilizing the optimized single-layer perovskite thin film. Consequently, green electroluminescence at 523 nm, featuring a full width at half maximum (FWHM) of 20 nm and a chromaticity coordinate of (0.121, 0.800), was successfully generated from the PeLEC. This showcases the viability of the mentioned methodology for the future fabrication of light-emitting devices.

Study of the free carrier characteristics and surface morphology of AlGaAs/GaAs thin films deposited using MOCVD

Ultra-low loss optical thin films find broad applications in fields such as vertical-cavity surface-emitting lasers and optical atomic clocks. The main optical losses in AlGaAs/GaAs distributed Bragg reflectors (DBRs) prepared using metal-organic chemical vapor deposition (MOCVD) arise from absorption loss caused by free carriers within the layers and scattering loss caused by surface roughness. In this study, we fabricated AlGaAs and GaAs single-layer thin films with varying Al compositions on substrates of three crystal orientations and under different V/III ratios. The dependence of carrier concentration and surface morphology on different substrates and growth conditions was investigated. Thin films grown on substrates with three different crystal orientations exhibited three distinct growth modes (step-flow mode, SK mode, and FM mode). The impact of the V/III ratio on the growth mode was found to be complex. Higher V/III ratios resulted in poorer morphology for films grown on (100) substrates, while better morphology was observed on (211) B substrates. Furthermore, the surface morphology of films grown on (100) 15° off substrates showed less sensitivity to changes in the V/III ratio. With increasing Al composition, the carrier concentration of the films significantly increased. Elevating the V/III ratio proved effective in suppressing the incorporation of carbon, thereby reducing the carrier concentration of AlGaAs films. GaAs films exhibited a low carrier concentration at an appropriate V/III ratio. Additionally, the distinct abilities of different substrates to adsorb impurities exerted a significant impact on the carrier concentration of the films. This study demonstrates that, under optimal conditions, it is feasible to fabricate AlGaAs/GaAs Bragg mirrors with low carrier concentration and relatively small roughness on (100) 15° off substrates.

Constructing highly efficient and ultra-stable (against Temperature, Humidity and Sunlight) luminescent solar concentrators by using dendritic CsPbBr3@SiO2 particles

Conventional perovskite quantum dots (PQDs) suffer long-term stability, further limiting practical application of luminescent solar concentrators (LSCs). In this work, novel dendritic CsPbBr3@SiO2 particles with bright solid-state green light emission and 46 % of photoluminescence quantum yield (PLQY) have first been synthesized via one-step solid-phase calcination method. The dendritic CsPbBr3@SiO2 particles have then been used as fluorescent material for construction of LSCs along with using organosilicon polymers with better compatibility as waveguide materials. Single-layer thin film LSCs and overall curing LSCs are easily prepared by the casting and curing method, exhibiting high external optical efficiency (ηopt) of 7.88 % and 10.92 %, respectively. The maximum internal quantum efficiency (ηint) of thin film LSCs and overall curing LSCs reach 45.09 % and 44.07 %, respectively, while their maximum external quantum efficiency (ηext) of 29.42 % and 34.07 % are obtained, respectively. Importantly, both types of LSCs show excellent stability, maintaining above 92 % of the initial ηopt under high-relative-humidity (RH = 90 %), high-temperature (60 °C) and sunlight exposure conditions for two weeks or room temperature environment for twenty weeks. Moreover, both types of LSCs at optimal conditions have good transparency (>40 % over 515 nm of light wavelength). Otherwise, both types of LSCs have higher ηopt than that of the previous related work.

Quantification of Unsupported Thin-Film X-ray Spectra Using Bulk Standards.

A quantification model which uses standard X-ray spectra collected from bulk materials to determine the composition and mass thickness of single-layer and multilayer unsupported thin films is presented. The multivariate model can be iteratively solved for single layers in which each element produces at least one visible characteristic X-ray line. The model can be extended to multilayer thin films in which each element is associated with only one layer. The model may sometimes be solved when an element is present in multiple layers if additional information is added in the form of independent k-ratios or model assumptions. While the algorithm is suitable for any measured k-ratios, it is particularly well suited to energy-dispersive X-ray spectrometry where the bulk standard spectra can be used to deconvolve peak interferences in the thin-film spectra. The algorithm has been implemented and made available in the Open Source application National Institute of Standards and Technology DTSA-II. We present experimental data and Monte Carlo simulations supporting the quantification model.

Electronic comprehension of exchange bias effect in Sr2CoRuO6−δ thin-film

Sr2CoRuO6 in its bulk form shows spin glass behavior with a transition temperature of 95 K, and in its epitaxial thin film, it shows similar behavior with a transition temperature of 135 K. We have studied the structural, electronic, and magnetic properties of a polycrystalline thin film of oxygen-deficient Sr2CoRuO6−δ (SCRO), which shows ferrimagnetic or glassy behavior up to room temperature. The presence of oxygen deficiency causes multivalent cations Co3+ and Co2+ and Ru4+ and Ru5+, which introduces various kinds of magnetic interactions between Co3+–O–Co2+, Co3+–O–Ru4+, Co2+–O–Ru4+, Co3+–O–Ru5+, and Co2+–O–Ru5+ exchange paths, producing unusual exchange bias effects in the single layer thin film of SCRO. The interionic charge transfer between Co and Ru ions as a result of the negative charge transfer energy of the system helps in visualizing the unconventional exchange bias effect in the system.

Optical, Electrical and Structural Properties of ITO/IZO and IZO/ITO Multilayer Transparent Conductive Oxide Films Deposited via Radiofrequency Magnetron Sputtering

In this study, we investigated the potential of multilayer TCO structures, specifically those made up of Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO), for crystalline silicon heterojunction solar cells (SHJ). We used the radiofrequency (RF) magnetron sputtering method to deposit various thin-film structures under various deposition temperatures and evaluated their electrical, optical, and morphological properties. The objective was to obtain films with lower sheet resistances and higher transmittances than those of single-layer thin films. Our results show that the ITO/IZO/ITO/IZO/ITO multilayer film structure deposited at 200 °C achieves the best sheet resistance of 18.5 Ohm/sq and a high optical transmittance of over 90% at a 550 nm wavelength. This indicates that multilayer TCO structures have the potential to be more optically and electrically efficient, and that they can improve the performance of optoelectronic devices. Finally, a power conversion efficiency of 17.46% was obtained for a silicon heterojunction (SHJ) solar cell fabricated using an ITO/IZO/ITO/IZO/ITO multilayer film structure deposited at 200 °C as a front TCO. Our study provides valuable insights into the field of TCOs and offers a promising avenue for future research.

Single-layer SrTiO3 film and SiO2/SrTiO3 composite film white electroluminescence performance comparison

Single-layer SrTiO3 film and SiO2/SrTiO3 composite film electroluminescence (EL) devices were fabricated on n-Si substrate though vacuum electron vapor deposition (EBVD) technique. The film layers in the device were analyzed using various detection methods to determine their microstructure and composition, and the EL properties of both types of devices were compared. EL experimental results show that both devices can emit white light visible to the naked eye when the forward bias is applied. Moreover luminescence intensity of SiO2/SrTiO3 composite thin film devices is much higher than that of single-layer SrTiO3 thin film devices. The EL spectrum analysis of the device samples shows that there are three luminescence peaks in both types of devices, and they are located in the blue, yellow and red regions. Three emission peaks of single-layer SrTiO3 thin film devices are located at 460 nm (blue region), 580 nm (yellow region) and 685 nm (red region). Three luminescence peaks of SiO2/SrTiO3 composite thin film devices are located at 460 nm (blue region), 585 nm (yellow region) and 716 nm (red region). In composite film devices, SiO2 acts as an electron barrier layer, confining electrons to the SrTiO3 film layer and increasing the chance for the electrons in the SrTiO3 conduction band to participate in the composite luminescence. As a result, the blue peak emission intensity of the SrTiO3 composite film device is significantly enhanced, while the overall white light emission intensity of the composite thin film device is greatly improved. Additionally, the color coordinates of SiO2/SrTiO3 composite film device is closer to those of standard white light according to CIE standards.

Effect of copper and silver as a middle layer on the structural, electrical, photocatalytic, and optical properties of ZnS/metal/ZnS films for optoelectronics applications

In this work, we utilized the thermal vacuum evaporation technique to fabricate ZnS single-layer thin films, ZnS/Cu/ZnS (ZCZ), and ZnS/Ag/ZnS (ZAZ) multilayer thin films. The influence of the middle layer of metals like copper and silver on the physical properties of ZnS/metal/ZnS multilayers is investigated. The results of the X-ray investigation demonstrate that the samples are polycrystalline, with a cubic ZnS structure and texture (111) at 2 = 29.1°. The optical investigation using Tauc’s approach yields energy gap values of 3.76 eV, 3.68 eV, and 3.6 eV for ZnS, ZCZ, and ZAZ films, respectively. CO2 gas sensing efficiency of ZnS, ZCZ, and ZAZ films were found to be at different operating temperatures. The optimal temperatures for ZnS, ZCZ, and ZAZ thin films were determined to be 483 K, 693 K, and 693 K, respectively. Under ultraviolet (UV) irradiation, the photocatalytic activity of ZnS, ZCZ, and ZAZ films for the degradation of methylene blue were studied. The results suggest that the metal intermediate layer is significant in improving the photocatalytic capabilities of ZnS films. When compared to ZnS single layer film (degradation efficiency of 15% after 180 min of UV irradiation), ZAZ multilayer film demonstrates the highest photocatalytic activity (degradation efficiency of 50% after 180 min of UV irradiation). The mechanism of the metal middle layer’s improved UV photoactivity is briefly discussed.

Design Rules for Resistors, Capacitors and Inductors Fabricated From Single Layer Y-Ba-Cu-O Thin Films With Focused Helium Ion Beam Irradiation

Yttrium barium copper oxide (YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-<inline-formula><tex-math notation="LaTeX">$\delta$</tex-math></inline-formula></sub> or YBCO) Josephson junctions fabricated using focused helium gas field ion sources show great promise for high transition temperature superconducting electronics. A unique feature of this technology is that it can also be utilized for the fabrication of resistors, capacitors and inductors in the same material and process step. The key to this method is that the electrical resistivity of high critical temperature superconductors is very sensitive to ion irradiation. The ions introduce disorder into the material which causes it to undergo a metal-to-insulator transition. By carefully controlling the position of the beam and ion dose delivered to the material, insulating pathways and reduced critical temperature metallic regions can be fabricated to construct the aforementioned passive components. We have prepared this manuscript to serve as a guide for circuit designers utilizing this process. We discuss the capabilities and limitations of helium ion beam lithographic patterning of YBCO and estimate the practical ranges of the values that can be obtained for resistors, capacitors and inductors in single layer thin films. Estimates are provided for two processes: one with the highest resolution with the smallest beam diameter (0.5 nm) and another based on the highest source current (100 pA) for fastest write time.