Oxide Thin Films Research Articles

Flexible epitaxial LiNbO3 thin film with ferroelectricity and nonlinear optical response

Flexible or wearable devices are of great interests in the modern technologies, and oxide thin films are critical components for such applications. In this work, epitaxial LiNbO3 (LNO) thin film integrated on flexible mica substrate has been achieved. Al-doped ZnO (AZO) layer has been first deposited as buffer layer to obtain the epitaxial LNO film, furthermore AZO serves as bottom electrode for electrical measurement. The as-deposited LNO film exhibits high epitaxial quality with c-direction growth. The transmittance measurement indicates the high transparency of the film, ～85 % in visible range and ～90 % in near infrared region up to 1500 nm. The second harmonic generation (SHG) measurement confirms the nonlinearity of the flexible LNO film. The LNO/AZO/mica film also presents apparent ferroelectric response. Overall, the high-quality LNO integrated on flexible mica could be potentially applied in wearable optical and electrical devices.

Synthesis of Mn doped nanostructured zinc oxide thin films for H2 gas sensing

Thin films of zinc oxide and (ZnO:Mn) with 1% and 3% concentrations were created at 400 °C by spray pyrolysis. According to X-ray diffraction (XRD) investigation, ZnO films are polycrystalline and have a cubic structure with a distinct peak in one direction (101). The grain size increases as manganese content rise, from 12.66 nm to 14.66 nm. While the strain (ε) for ZnO reduced after manganese doping, it decreased from 27.36 to 23.63. Surface topography and nanostructure study reveal that as the manganese (Mn) content of ZnO films increased, cluster grain size, average roughness, and root mean square roughness (Rrms) all significantly reduced. SEM images show substantial morphological changes from flat islands to spherical nano-grains post-manganese via Mn content. The average transmittance was >70% in the visible area for Undoped ZnO and 1, 3% Manganese doping optical transmittance demonstrates exceptional optical transparency. When doping levels are increased by 1% or 3%, the absorption coefficient rises. The optical band gap widens in ZnO: Mn film for allowed direct transition has been decreased from (3.32 to 3.21) eV. Results illustrate that the films' refractive index and extinction coefficient decreases with increasing Mn Doped. Hydrogen gas decreases resistance in ZnO films, suggesting p-type behavior. Doping with 3% Mn increases resistance. Decreased sensitivity with higher Mn content after hydrogen gas exposure indicates increased electrical resistance in the film.

Performance investigation of silicon nitride (SiNx) layer doped with twin thin films of gallium and zinc oxide for solar cell

Performance investigation of silicon nitride (SiNx) layer doped with twin thin films of gallium and zinc oxide for solar cell

Swelling of Thin Graphene Oxide Film in Water Vapor Studied by In Situ Spectroscopic Ellipsometry.

Graphene oxide (GO) is obtained by the chemical treatment of graphene sheets, resulting in decoration with oxygen-containing functional groups. In the work presented here, we examined marked changes that occur in a thin film of parallel aligned GO sheets when exposed to water vapor at various pressures. It was found that exceptionally fast and substantial water uptake and release occur that is accompanied by major changes in GO interlayer spacing. These characteristics were obtained in situ with spectroscopic ellipsometry. At 99% relative humidity (RH) and 25 °C, the interlayer spacing became 1.41 nm, which recovers to ∼0.8 nm within 30 s when exposed to 10% RH. Besides layer thickness values, uniaxial optical constants for the GO vs RH were derived from the ellipsometry data. Molar refraction theory was applied that indicated monolayer water formation at ∼91% RH at 25 °C upon water adsorption. Our findings contribute to the understanding of the interaction between GO and its environment. The very outspoken effect of external water vapor pressure on GO water content, interlayer spacing, and optical properties can be utilized in sensing and separation devices, subnanometer positioning, chemical switches, and environmentally aware materials.

Altering the physical properties of NiO thin films grown through the ultrasonic spray pyrolysis method by incorporating impurity lead dopants

The technology of p-type transparent semiconductors is utilized in various fields, and enhancing their performance holds industrial significance. Thus, improving the versatility and efficiency of the p-type transparent conducting oxides (TCO) has become critical for the semiconductor industries and technologies. To be used as hole carrier layes in optoelectronic devices, this study aimed to modify the physical features of nickel oxide (NiO) through a doping approach which may broaden and strengthen the usage of NiO. A cost-effective ultrasonic pyrolysis spray technique was employed for pure and lead (Pb) doped nickel oxide thin film production. The influence of the lead concentration on optical, structural, and morphological traits of the NiO nanostructures was examined via various analyses, including energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), Photoluminescence, UV–visible spectroscopy, X-Ray Diffraction, and Raman spectroscopy, were utilized to investigate the optical and structural characteristics of these films. In correlation, the X-Ray Diffraction results indicated that the Pb doping induced strain and altered lattice parameters of the grown nanostructures while the cubic phase of NiO maintained. The crystallite size of NiO samples ranged from 31.49 nm to 18.75 nm based on Pb doping concentration which was notably influenced by species and doping content. The UV–vis measurements demonstrated that optical parameters, such as optical band gap, were sensitive to Pb doping ratios. The Raman spectrum analysis confirmed the successful incorporation of Pb ions into NiO. Additionally, the intensity of the PL spectra decreased with increasing Pb content, offering potential applications as window layers in solar cells, smart windows, and other optoelectronic devices.

Vacancy Ordering in Ultrathin Copper Oxide Films on Cu(111).

Oxide thin films grown on metal surfaces have wide applications in catalysis and beyond owing to their unique surface structures compared to their bulk counterparts. Despite extensive studies, the atomic structures of copper surface oxides on Cu(111), commonly referred to as "44" and "29", have remained elusive. In this work, we demonstrated an approach for the structural determination of oxide surfaces using element-specific scanning tunneling microscopy (STM) imaging enhanced by functionalized tips. This approach enabled us to resolve the atomic structures of "44" and "29" surface oxides, which were further corroborated by noncontact atomic force microscopy (nc-AFM) measurements and Monte Carlo (MC) simulations. The stoichiometry of the "44" and "29" frameworks was identified as Cu23O16 and Cu16O11, respectively. Contrary to the conventional hypothesis, we observed ordered Cu vacancies within the "44" structure manifesting as peanut-shaped cavities in the hexagonal lattice. Similarly, a combination of Cu and O vacancies within the "29" structure leads to bean-shaped cavities within the pentagonal lattice. Our study has thus resolved the decades-long controversy on the atomic structures of "44" and "29" surface oxides, advancing our understanding of copper oxidation processes and introducing a robust framework for the analysis of complex oxide surfaces.

P‐13: Excessive Oxygen induced Threshold Voltage Shifts in High Mobility Top‐Gate PrIZO TFTs

The top gate self‐alignment (TGSA) Praseodymium‐doped indium zinc oxide (PrIZO) thin film transistor (TFT) was fabricated with different process condition in our production line, and high field effect mobility of 40.83 cm2 V‐1 s‐1 was obtained by regulating the GI and ILD parameters. At the same time, the devices show excellent stability with PBTS of 0.52 V and NBTIS of ‐0.9 V, indicating its potential in overcoming the trade‐off between mobility and reliability.

Photosensitive iron–aluminum oxide gas sensor

In this study, the structural, topographic, and optical properties of iron–aluminum oxide (AlxFe2−xO3, 1 > x > 0) thin film grown by co-sputtering method were investigated. Firstly, AlxFe2−xO3 films grown by magnetron RF–DC co-sputtering method were annealed at 540 °C and then XRD analyses were performed. The absorption measurement, Raman shift, XPS, gas sensor measurements, and SEM images were taken, respectively. The band gap energy of the AlxFe2−xO3 samples was obtained and measured as approximately 2.41 eV, and different peaks at various intensities were seen in the XRD analysis. According to the XRD analysis of the AlxFe2−xO3 semiconductor, the peaks occurred at 33.42°, 41.16°, and 54.43° and the XRD analysis results show that the structure is polycrystalline. As seen in the measurement of the AlxFe2−xO3 gas sensors, acoustic gas sensorsgas sensor, the current value increased with the flow of hydrogen gas. This means that the oxygen that hydrogen detached from the thin film surface contributes to the conductivity of the remaining electrons in the structure, which means that the thin film was an n-type semiconductor. It was seen that the AlxFe2−xO3 gas sensor was very sensitive to light. During the feature measurement, it was seen that the current value measured under the light increases considerably.

Enhanced optoelectronic and catalytic properties of Sm doped SnO2 thin films

Herein, we report the optoelectronic and malachite green (MG) aqueous dye model pollutant degradation characteristics of samarium (Sm) doped tin oxide (SnO2:Sm) thin films deposited on glass substrate by chemical spray pyrolysis technique. The tetragonal crystal structure and polycrystalline nature were elucidated from X-ray diffraction (XRD) analysis, and the calculated crystallite size using Scherrer's relation was found to vary between 36 and 45 nm. A high optical transparency of 92 % was achieved for SnO2:Sm (3 wt%). The extrapolation of linear fit indicates a slight decrement in the band gap. Energy dispersive X-ray analysis (EDAX) confirmed the presence of Sn, O and Sm elements and their composition. The quantitative compositional percentage of Sn, O and Sm was determined by X-ray photoelectron spectroscopy (XPS) analysis. The scanning electron micrographs (SEM) showed polyhedron-like shaped grains with cracks and void-free film surface. The 3 wt% Sm:SnO2 thin film exhibited a higher average surface roughness (19.63 nm) than other films. Strong ultraviolet (365 nm), blue (493 nm), and green (520 nm) emissions were observed for all the films, as recorded by photoluminescence (PL) studies. High electron concentration (7.9 × 1020/cm3), low resistivity (0.356 × 10−3 Ω cm), and a high figure of merit (FOM, 5.11 × 10−2 Ω−1) were obtained for 3 wt % of SnO2:Sm thin films. Furthermore, a relatively high photocurrent (8.22 mA) was attained for the 3 wt% Sm:SnO2 thin film. Enhanced photocatalytic efficiency (95 %) was achieved for the 4 wt% Sm:SnO2 film against MG dye aqueous solution. The results obtained in the present study demonstrate high optical transparency, electrical conductivity, enhanced FOM, and photocatalytic degradation efficiency for 3 and 4 wt% Sm-doping, respectively. Therefore, Sm-doped SnO2 could be useful for developing and designing novel devices for optoelectronic and photocatalytic applications.

Fabrication of zinc oxide and phosphorus optical thin films and comparison of their effect on silicon solar cell efficiency

Fabrication of zinc oxide and phosphorus optical thin films and comparison of their effect on silicon solar cell efficiency

97‐3: Late‐News Paper: Enhanced IGZO TFT Performance with Atomic Layer Deposition Parameter Optimization for Large OLED Displays

In this comprehensive study, we rigorously evaluated the applicability of amorphous indium gallium zinc oxide (a‐IGZO) thin films synthesized using atomic layer deposition (ALD) technology in the field of large‐area organic light‐emitting diode (OLED) TVs. The key term to display production is the distribution of device characteristics, and maintaining uniformity can improve productivity yield and product quality. The purpose of this paper is to present guidelines for early application in industry through the process variable exploration results of ALD deposition equipment. The process parameters studied are process pressure and oxygen partial pressure (PO2). We have secured a method to secure device characteristics suitable for display technology through the correlation between a‐IGZO thin film characteristics and device characteristics through corresponding parameters. Our empirical data strongly demonstrate that the threshold voltage (Vth) stabilizes near 0.0 V and consistently achieves device mobility exceeding 15 cm2/Vs. In particular, this study shows that the variability of the Vth characteristic, which is limited to a narrow range of less than ±0.1V, is greatly reduced, and the mobility dispersion is also greatly reduced to less than ±1cm2/Vs. A deeper analytical exploration revealed that the pivotal factors affecting device performance are closely related to oxygen vacancies (Vo) and their dynamic interactions with oxygen molecules. These results will improve the uniformity of device characteristics, and it is believed that the introduction of ALD technology into future display technology will demonstrate improvements in the performance and quality of display products.

Effect of metal source variation in cuprous oxide thin films deposited by chemical bath deposition

Effect of metal source variation in cuprous oxide thin films deposited by chemical bath deposition

Enhancement of electro-optical properties of aluminum magnesium oxide thin films through controlled graphene oxide doping

Enhancement of electro-optical properties of aluminum magnesium oxide thin films through controlled graphene oxide doping

P‐221: All Inkjet‐Printed Inverted Electroluminescent Quantum Dot Light Emitting Diode Display Based on Metal Oxide Thin Film Transistors

A 12.4‐inch inverted cadmium‐free electroluminescent quantum dot (QD) light emitting diode (LED) display panel based on metal oxide thin film transistors (TFTs) is demonstrated. The backplane of our panel is fabricated by using multiple steps of photolithography processes, and pixel/scan driver circuits are composed by n‐type indium‐gallium‐zinc oxide TFTs. Especially, each sub‐pixel has internal compensation circuit which compensates the threshold voltage of its own driving TFT. Different from the conventional structure, since our QD LEDs have inverted structures, electroluminescent layers from the electron injection layer to the hole injection layer are constructed by sequential inkjet‐printing processes. Our inverted electroluminescent QD LED display based on metal oxide TFTs is very promising structure for premium large‐format displays for the next generation due to its superb performance and cost‐effectiveness.

Study of The Optical Properties of Copper Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique

Study of The Optical Properties of Copper Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique

Study on structural, optical, and electrical properties of yttrium doped molybdenum oxide thin film and its MIS diode performance

In this study, Orthorhombic pure MoO3 and various weight percentages of Y-doped MoO3 nanostructure arrays were successfully deposited using the simple jet nebulizer spray pyrolysis process at an ideal substrate temperature of 500 °C. In order to create metal-insulator-semiconductor-based Schottky barrier diodes, Y-doped MoO3 nanostructure arrays were employed as an insulating layer. The influence of Y-doped MoO3 concentration during the deposition process was carefully analyzed in relation to the structural, morphological, optical, and electrical characteristics of Y-doped MoO3 nanostructure array films. The produced films' crystalline nature with an orthorhombic phase was shown by the XRD pattern. An FE-SEM was used to analyse the solidly linked plate-like structure of Y-doped MoO3 at higher concentrations of 6 wt%. The EDAX spectrum was used to confirm the stoichiometric relationship between the elements O, Mo, and Y. The band gap values of the Y-doped MoO3 were determined using UV–Vis spectroscopy to range from 3.3 to 3.18 eV with doped concentrations. The film made with 6 wt% Y doped MoO3 showed a sharp improvement in electrical conductivity according to a DC electrical analysis. Notably, MIS diode made with 6 wt% Y-doped MoO3 in particular showed a low ideality factor (n = 2.63), strong photosensitivity (PS = 17,509.62%), responsivity of 738 mA/W, and a maximum QE of 97.49% under illumination (130 mW/cm2). Additionally, a 6 wt percent Y-based diode obtained a greater detectivity of D* = 7.16 1009 jones in a dark environment condition.

Optical properties of the interface between indium tin oxides thin films and laser-deposited single-walled carbon nanotubes

Optical properties of the interface between indium tin oxides thin films and laser-deposited single-walled carbon nanotubes

Route Toward Sustainable Oxide TFTs: Does Thin Film Oxide Technology Offer a Pathway Toward More Sustainable Electronics?

Route Toward Sustainable Oxide TFTs: Does Thin Film Oxide Technology Offer a Pathway Toward More Sustainable Electronics?

Chemical Environment and Structural Variations in High Entropy Oxide Thin Film Probed with Electron Microscopy.

We employ analytical transmission electron microscopy (TEM) to correlate the structural and chemical environment variations within a stacked epitaxial thin film of the high entropy oxide (HEO) Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (J14), with two layers grown at different substrate temperatures (500 and 200 °C) using pulsed laser deposition (PLD). Electron diffraction and atomically resolved STEM imaging reveal the difference in out-of-plane lattice parameters in the stacked thin film, which is further quantified on a larger scale using four-dimensional STEM (4D-STEM). In the layer deposited at a lower temperature, electron energy loss spectroscopy (EELS) mapping indicates drastic changes in the oxidation states and bonding environment for Co ions, and energy-dispersive X-ray spectroscopy (EDX) mapping detects more significant cation deficiency. Ab initio density functional theory (DFT) calculations validate that vacancies on the cation sublattice of J14 result in significant electronic and structural changes. The experimental and computational analyses indicate that low temperatures during film growth result in cation deficiency, an altered chemical environment, and reduced lattice parameters while maintaining a single phase. Our results demonstrate that the complex correlation of configurational entropy, kinetics, and thermodynamics can be utilized for accessing a range of metastable configurations in HEO materials without altering cation proportions, enabling further engineering of functional properties of HEO materials.

Temperature modulation enables in situ growth of gallium oxide nanostructures on thin films exhibiting diverse morphologies

In this study, we successfully synthesized three gallium oxide thin films on (0001)-faceted Al2O3 substrates using hydrogen-reduced chemical vapor deposition (CVD) at different deposition temperatures, resulting in distinct morphologies and crystalline phases. These films consist of two pure-phase β-Ga2O3 films and one mixed-phase film comprising both β- and ε-Ga2O3 phases. The mixed-phase samples were subsequently annealed at high temperatures to obtain pure-phase β-Ga2O3 thin films. Furthermore, by precisely controlling the growth temperature, we achieved in-situ formation of Ga2O3 nanostructures (nanowires and nanoribbons) on the surface of the β-Ga2O3 thin films. The presence of different dominant crystal planes in the samples was confirmed through X-ray diffraction analysis (XRD) for verification purposes. In directly grown β-Ga2O3 films, the (−201) plane emerged as the primary crystallographic plane, while both the (−201) and (401) planes dominated in β-Ga2O3 films obtained via ε-Ga2O3 film annealing. Raman spectroscopy findings further supported these observations regarding the crystalline phase of the films as observed through XRD analysis. Scanning electron microscopy (SEM) images revealed distinct film morphologies resulting from variations in deposition temperatures. A flatter surface was observed when a higher proportion of ε-Ga2O3 was present in the film, however, regular cracking occurred after annealing. Atomic Force Microscope (AFM) images demonstrated that at a deposition temperature of 800 °C, regular steps were present on the film's surface. Mixed-phase films exhibited hillock morphology that disappeared after annealing, leading to a decrease in the surface roughness in root mean square (RMS) value. By elevating the growth temperature, a significantly enhanced density of gallium oxide nanoribbons can be seamlessly integrated onto the film surface. The transferred nanoribbons exhibit an ultra-thin profile with a minimum thickness of merely 12 nm, rendering them more slender and economically advantageous in comparison to conventional mechanical stripping methods. This study presents a CVD-based approach for growing gallium oxide thin films with varying morphologies by employing temperature modulation and demonstrates an innovative one-step method for growing nanostructures on gallium oxide films in situ, providing valuable insights for future device development involving gallium oxide.