Pulsed Laser Deposition Research Articles

Effect of substrate-induced compressive strain on protonation of SrCoO2.5 epitaxial films

Abstract In this study, we grew (010)-oriented epitaxial films of brownmillerite-structured SrCoO2.5 on various substrates whose lattice mismatch against SCO ranged from 0 to -2.9% by pulsed laser deposition and investigated the effect of substrate-induced strain on their protonation in field effect transistor structures with gate layers consisting of Nafion membranes. We found that the H concentration of the SCO films that were fully compressive-strained by up to 1.3 % was ~1.7 and that it was almost independent of the magnitude of the substrate-induced strain. We also found that the H content of the strain-partially-relaxed film with a residual compressive strain of 1.3% was lower, ~1.3. These results indicate that lattice deformations arising from substrate-induced strain have insignificant effects on protonation, while lattice defects and dislocations introduced upon strain relaxation, which hinders proton diffusion in the films’ lattices, dominantly affect protonation in SrCoO2.5 films

Unraveling the thickness-dependent high photoconductivity in BaSnO3 thin films: insights from ultrafast charge carrier dynamics

Abstract Barium stannate, a perovskite-structured semiconductor, is gaining significant attention for its potential in high-performance UV photodetectors and optoelectronic applications. This study investigated the photo-response of epitaxial BaSnO3 (BSO) thin films grown using pulsed laser deposition. Our findings revealed an exceptionally high photo-response in BSO films having thicknesses (90, 270, and 360 nm). Detailed optical analyses were conducted to elucidate the photoconductive response’s mechanisms, including photoluminescence (PL), time-resolved PL, and the ultrafast transient spectroscopy. Notably, ultrafast transient spectroscopy was employed for the first time on this material. Leveraging BSO’s wide bandgap (3.4 eV), photoconductivity measurements in the UV range showed a peak responsivity of 5 A W−1 at 5 V with a 360 nm film and a response time of 470 ms. The transient spectroscopy reveals the thickness-dependent carrier dynamics, such as carrier relaxation, carrier trapping in mid-gap states, and recombination. Specifically, observed trapping times were approximately 6 ps for 360 nm thickness, 26 ps for 270 nm thickness, and 59 ps for 90 nm thickness of BSO thin film. This research enhances the understanding of the photoconductive behavior of barium stannate thin films and lays the groundwork for optimizing BSO-based UV-sensitive optoelectronic devices.

The Influence of Various Parameters on the Ablation and Deposition Mechanisms in Pulsed Laser Deposition

The Influence of Various Parameters on the Ablation and Deposition Mechanisms in Pulsed Laser Deposition

Boosting the energy storage performance of BCZT-based capacitors by constructing a Schottky contact.

Multilayer thin films composed of dielectric Ba0.7Ca0.3Zr0.2Ti0.8O3 (BCZT) and oxygen-deficient BCZT (BCZT-OD) were fabricated on (001)-oriented NSTO substrates using the pulsed laser deposition (PLD) technique. Unlike conventional approaches to energy storage capacitors, which primarily focus on compositional or structural modifications, this study explored the influence of the layer sequence and periodicity. The interface between the NSTO substrate and the BCZT-OD layer forms a Schottky barrier, resulting in electric field redistribution across the sublayers of the BCZT/BCZT-OD//(1P) thin film. This redistribution delays the breakdown of the BCZT layer, significantly enhancing the film's electric breakdown strength. Furthermore, mathematical analysis reveals that the electric field redistribution amplifies dipole polarization, with BCZT-OD-initiated multilayers exhibiting superior polarization compared to those with equivalent periodicity but different starting layers. Consequently, the BCZT/BCZT-OD//(1P) multilayer achieves an exceptional recoverable energy density (Wrec) of 150.22 J cm-3 and an energy efficiency (η) of 83.07%, surpassing typical performance benchmarks for BCZT-based thin films. These findings are corroborated by comprehensive structural characterization studies, performance evaluations, and finite element simulations, which further validate the role of the Schottky barrier in enhancing voltage endurance. Analogous to "Tian Ji's Strategy for Horse Racing", this work achieved high Wrec by sacrificing the ferroelectricity of the negative side of the P-E loop, introducing an innovative paradigm for designing and developing next-generation electronic devices.

High-performance solar-blind ultraviolet photodetector arrays based on two-inch ϵ-Ga2O3 films for imaging applications

Abstract To achieve high-quality solar-blind imaging applications based on ultrawide bandgap semiconductor photodetectors, it is crucial to fabricate highly uniform wafer-scale films. In this work, we demonstrate the fabrication of exceptionally uniform two-inch ε-Ga2O3 thin films on sapphire substrates using an off-axis pulsed laser deposition method. The two-inch ε-Ga2O3 films exhibit remarkable uniformity across key parameters, including thickness, crystalline quality, bandgap, and surface roughness, with an inhomogeneity ratio less than 5%. Additionally, these films are preferentially oriented along the (001) crystal plane. At 20 V bias, the individual ε-Ga2O3 photodetector demonstrates outstanding solar-blind ultraviolet (UV) photodetection performance, with a responsivity of 52.77 A/W at 240 nm, an external quantum efficiency of 2.7×104%, a dark current of 5.5×10-11 A and a UV–visible rejection ratio of 1.2×104. Furthermore, the 10×10 photodetector arrays fabricated on two-inch ε-Ga2O3 films exhibit highly uniform photodetection performance, with photocurrent deviations remaining within one order of magnitude and a maximum standard deviation of ~8%. High-contrast optical imaging of the letters of “NIMTE” is successfully achieved using the 10×10 photodetector array detector. This work provides valuable insights for fabricating wafer-scale uniform ε-Ga2O3 films and achieving high-quality solar-blind UV imaging applications.

P-(001)NiO/n-(0001)ZnO heterojunction devices grown by pulsed laser deposition technique

p-(001)NiO/n-(0001)ZnO heterojunction devices grown by pulsed laser deposition technique

Large enhancement of ferroelectric properties of perovskite oxides via nitrogen incorporation.

Perovskite oxides have a wide variety of physical properties that make them promising candidates for versatile technological applications including nonvolatile memory and logic devices. Chemical tuning of those properties has been achieved, to the greatest extent, by cation-site substitution, while anion substitution is much less explored due to the difficulty in synthesizing high-quality, mixed-anion compounds. Here, nitrogen-incorporated BaTiO3 thin films have been synthesized by reactive pulsed-laser deposition in a nitrogen growth atmosphere. The enhanced hybridization between titanium and nitrogen induces a large ferroelectric polarization of 70 μC/cm2 and high Curie temperature of ~1213 K, which are ~2.8 times larger and ~810 K higher than in bulk BaTiO3, respectively. These results suggest great potential for anion-substituted perovskite oxides in producing emergent functionalities and device applications.

Magnetic-proximity-induced anomalous Hall effect at the EuO/Sb2Te3 interface

Time-reversal symmetry breaking of a topological insulator phase generates zero-field edge modes which are the hallmark of the quantum anomalous Hall effect (QAHE) and of possible value for dissipation-free switching or non-reciprocal microwave devices. But present material systems exhibiting the QAHE, such as magnetically doped bismuth telluride and twisted bilayer graphene, are intrinsically unstable, limiting their scalability. A pristine magnetic oxide at the surface of a TI would leave the TI structure intact and stabilize the TI surface, but epitaxy of an oxide on the lower-melting-point chalcogenide presents a particular challenge. Here we utilize pulsed laser deposition to grow (111)-oriented EuO on vacuum cleaved and annealed Sb2Te3(0001) surfaces. Under suitable growth conditions, we obtain a pristine interface and surface, as evidenced by x-ray reflectivity and scanning tunneling microscopy, respectively. Despite bulk transport in the thick (2 mm) Sb2Te3layers, devices prepared for transport studies show a strong AHE, the necessary precursor to the QAHE. Our demonstration of EuO-Sb2Te3epitaxy presents a scalable thin film approach to realize QAHE devices with radically improved chemical stability as compared to competing approaches.

Unlocking the Performance of Next-generation Non-volatile Capacitive Memory Devices with Ti-doped ZnO Nano Wires via Pulsed Laser Deposition

This paper investigates the impact of titanium (Ti) doping on zinc oxide (ZnO) nano wires (NWs) in non-volatile capacitive memory devices (NVCMDs) through fabrication and characterizations. ZnO NWs were fabricated using pulsed laser deposition (PLD), while Ti thin film (TF) was deposited via electron beam evaporation (e-beam). Field emission gun scanning electron microscopy (FEGSEM) confirmed the formation of ZnO NWs and Ti-doped ZnO NWs (Ti:ZnO NWs) on an n-type silicon (Si) substrates, with elemental compositions determined by energy dispersive X-ray spectroscopy (EDX). Structural characterization was conducted on the samples using high-resolution X-ray diffraction (HRXRD). Gold (Au) interdigitated electrodes (IDE) were employed to fabricate two distinct devices: Au IDE/ZnO NWs and Au IDE/Ti:ZnO NWs. Comparative analysis revealed that the Au IDE/Ti:ZnO NWs device exhibited a lower frequency dispersion fd value (0.025×109 F) compared to Au IDE/ZnO NWs device (0.029×109 F), indicating enhanced signal propagation due to Ti doping. The Au IDE/Ti:ZnO NWs device also demonstrated a high free charge carrier donor concentration ND value of 2.02×1012 /cm3, a significant trap concentration Nt value of 4.44×1011 /cm3 at an 8MHz frequency response. Additionally, it exhibited lower tangent loss (tan(δ)) value of 7430, maximum conductance Gmmax value of 13.40 mS, lower interface trap state density (ITSD) value of 2.05×1014 eV1 cm2, a maximum memory window (∆VMW) of 6.9V at ±15V, improved endurance, and superior data retention, making the Au IDE/Ti:ZnO NWs device a promising candidate for next-generation NVCMDs applications.

Energy storage performance and dielectric tunability of AgNbO3 ferroelectric films

AgNbO3 ceramics have attracted significant attention as environmentally friendly energy storage materials; however, their low energy densities limit further development. In this study, a 400- nm AgNbO3 films with a dense microstructure and flat surface is prepared by pulsed laser deposition. The dielectric tenability and hysteresis loops of the film reveal its ferroelectric nature. The dielectric tunability of the AgNbO3 film was 63.6% at 600kV/cm. The breakdown strength reached 1500kV/cm, resulting in a high recoverable energy density of 13.3J/cm3. The recoverable energy storage density of AgNbO3 films indicates good temperature stability with a variation of < 10% between 30 ℃ and 150 ℃ and good frequency stability with a variation of < 10% between 103Hz and 105 Hz. These results suggest that AgNbO3 dielectric films are promising energy storage materials.

Heteroepitaxial growth of PMN-PT thin films on SrTiO3 buffered III-V semiconductor GaAs by pulsed laser deposition

Heteroepitaxial growth of PMN-PT thin films on SrTiO3 buffered III-V semiconductor GaAs by pulsed laser deposition

Study of the performance of organic solar cells using SnO2 nanoparticles as electron transport layer growth by pulsed laser deposition

Study of the performance of organic solar cells using SnO2 nanoparticles as electron transport layer growth by pulsed laser deposition

Effect of different laser wavelengths on the optical properties of GaN/PSi and Al2O3/PSi thin films using the pulse laser deposition method

Effect of different laser wavelengths on the optical properties of GaN/PSi and Al2O3/PSi thin films using the pulse laser deposition method

Thickness effect on the evolution of superconducting properties in FeSe0.4Te0.6 thin films

Abstract A series of high-quality FeSe0.4Te0.6 epitaxial thin films with different thicknesses were fabricated on CaF2 substrates by pulsed laser deposition. With increasing the film thickness, the superconducting transition temperature is enhanced rapidly but deteriorates gradually in over thick films. The superconducting transition occurs in all films including the 5 nm one, and Tc above 21 K persists in the films with thicknesses from 45 to 180 nm. We find that Tc and the c-axis lattice constant show a nearly linear correlation, suggesting a strong interdependence between Tc and the lattice strain characteristics. The upper critical field, anisotropy and effective pinning energy are studied in detail for the 15, 60, 90 and 180 nm films. These observations provide key insights in understanding the thickness effect on the superconductivity of the FeSe0.4Te0.6 films.

Investigating Sensor Properties of Plasmonic Gold Nanoparticles Produced By Pulsed Laser Deposition

Plasmonic gold nanoparticles exhibit exceptional optical properties, particularly Lo-calised Surface Plasmon Resonance, which makes them ideal candidates for sensor applications. These nanoparticles are highly sensitive to changes in their surrounding environment, allowing for precise detection of molecular interactions and environ-mental shifts. In this study, we investigate the sensor properties of gold nanoparticles produced via Pulsed Laser Deposition, a clean and versatile method that allows for precise control over particle size, morphology, and distribution without the need for chemical reagents. Pulsed Laser Deposition process was optimized by adjusting laser fluence, pulse duration, and deposition time to produce gold nanoparticles with tuna-ble plasmonic properties. The structural and optical characteristics of gold nanoparti-cles were analyzed using scanning electron microscopy, and UV-Vis spectroscopy, confirming that the size and morphology of the particles were controllable through the deposition parameters. The sensor performance of gold nanoparticles was evalu-ated through localised surface plasmon resonance measurements, which demonstrated their sensitivity to small changes in the refractive index of the surrounding medium. Specifically, the shift in localised surface plasmon resonance peak was measured up-on exposure to different analytes, including protein A where a wavelength shift of 50 nm measured, indicating the high sensitivity of these nanoparticles for biosensing ap-plications. The results suggest that Pulsed Laser Deposition-produced gold nanoparti-cles possess promising sensor properties for real-time detection and environmental monitoring, offering an efficient and reproducible platform for a wide range of sens-ing applications.

OPTICAL, MORPHOLOGICAL, STRUCTURAL, AND PHOTOCATALYTICAL PROPERTIES OF PLASMONIC AU NPS PRODUCED BY PULSED LASER DEPOSITION

Plasmonic Au NPs exhibit exceptional optical, morphological, and structural properties, making them promising materials for applications in photocatalysis, sensing, and energy conversion. This study explores the synthesis and characterization of plasmonic gold NPs produced by pulsed laser deposition, a versatile physical vapor deposition technique. Pulsed Laser Deposition enables precise control over NP formation through tunable parameters such as laser fluence, ambient gas environment, and deposition duration. The resulting NPs were systematically analyzed to evaluate their optical properties, including localized surface plasmon resonance, as well as their morphological and structural attributes. The localized surface plasmon resonance behavior of the synthesized Au NPs was found to be highly dependent on particle size, shape, and distribution, as revealed by UV-Vis spectroscopy and electron microscopy. Structural analysis via X-ray diffraction confirmed the crystalline nature of the NPs, with lattice parameters correlating to their stability and catalytic efficiency. Photocatalytic activity tests demonstrated that the gold NPs could effectively degrade organic pollutants under visible light, leveraging their strong LSPR-induced hot electron generation and charge transfer properties. In this study, gold NP thin film was produced on microscopic glass by Pulsed Laser Deposition system. Gold NPs thin film photocatalyst efficiency 95.00% and reaction rate constant 0.39 min-1 were calculated. At the end of 210 min, MB dye was degraded and turned into high transparency due to localized surface plasmon resonance property of gold NP. The findings may provide valuable insights into the design and application of plasmonic Au NPs in photocatalysis and other advanced technologies.

Unraveling the Interplay Between Memristive and Magnetoresistive Behaviors in LaCoO3/SrTiO3 Superlattice‐Based Neural Synaptic Devices

AbstractMemristors and magnetic tunnel junctions are showing great potential in data storage and computing applications. A magnetoelectrically coupled memristor utilizing electron spin and electric field‐induced ion migration can facilitate their operation, uncover new phenomena, and expand applications. In this study, devices consisting of Pt/(LaCoO3/SrTiO3)n/LaCoO3/Nb:SrTiO3 (Pt/(LCO/STO)n/LCO/NSTO) are engineered using pulsed laser deposition to form the LCO/STO superlattice layer, with Pt and NSTO serving as the top and bottom electrodes, respectively. The results show that both memristive and magnetoresistive properties can coexist without any compromise in performance, and the values of ROFF/RON and tunnel magnetoresistance (TMR) ratio are both improved by ≈1000% compared to a single‐period heterostructure. Notably, the Pt/(LCO/STO)5/LCO/NSTO device demonstrates superior multilevel storage performance, characterized by extended endurance, reliable retention, high ROFF/RON ratio, significant TMR ratio, and fundamental synaptic behaviors. Furthermore, density functional theory (DFT) is employed to calculate the changes in oxygen vacancies, affecting the overall energy bands and magnetic moments in the monolayer and multi‐periodic structures. Simulations using the handwritten digit recognition classification achieve the highest accuracy of 94.38%. These attributes suggest that the devices hold considerable promise for application in data storage and neuromorphic computing, offering a platform for high‐density neural circuits in intelligent electronic devices.

Growth and properties of hybrid Au-Co0.8Ni0.2nanowires embedded in SrTiO3/SrTiO3(001).

We present a sequential growth scheme based on pulsed laser deposition, which yields dense arrays of ultrathin, match-shaped Au/CoNi nanopillars, vertically embedded in SrTiO3thin films. Analysis of the magnetic properties of these nanocomposites reveals a pronounced out-of-plane anisotropy. We show that the latter not only results from the peculiar nanoarchitecture of the hybrid films but is further enhanced by strong magneto-structural coupling of the wires to the surrounding matrix. Finally, we provide a detailed overview of the optical response of these vertical nanostructures. Combining ellipsometry measurements with finite-difference time-domain simulations allows us to assess the potential of our self-assembly approach, as well as its possible shortcomings, for producing hybrid thin films with well-tailored magneto-plasmonic properties.

Narrow-bandgap titanium sesquioxide with resonant metasurfaces for enhanced infrared absorption

We report on the structural, chemical, and optical properties of titanium sesquioxide Ti2O3 thin films on single-crystal sapphire substrates by pulsed laser deposition. The thin film of Ti2O3 on sapphire exhibits light absorption of around 25%–45% in the wavelength range of 2–10 μm. Here, we design an infrared photodetector structure based on Ti2O3, enhanced by a resonant metasurface, to improve its light absorption in mid-wave and long-wave infrared windows. We show that light absorption in the mid-wave infrared window (wavelength 3–5 μm) in the active Ti2O3 layer can be significantly enhanced from 30%–40% to more than 80% utilizing a thin resonant metasurface made of low-loss silicon, facilitating efficient scattering in the active layer. Furthermore, we compare the absorptance of the Ti2O3 layer with that of conventional semiconductors, such as InSb, InAs, and HgCdTe, operating in the infrared range with a wavelength of 2–10 μm and demonstrate that the absorption in the Ti2O3 film is significantly higher than in these conventional semiconductors due to the narrow-bandgap characteristics of Ti2O3. The proposed designs can be used to tailor the wavelengths of photodetection across the near- and mid-infrared ranges.

Rare-Earth Iron Garnet Superlattices with Sub-unit Cell Composition Modulation.

Oxide superlattices reveal a rich array of emergent properties derived from the composition modulation and the resulting lattice distortion, charge transfer, and symmetry reduction that occur at the interfaces between the layers. The great majority of studies have focused on perovskite oxide superlattices, revealing, for example, the appearance of an interfacial 2D electron gas, magnetic moment, or improper ferroelectric polarization that is not present in the parent phases. Garnets possess greater structural complexity than perovskites: the cubic garnet unit cell contains 160 atoms with the cations distributed between three different coordination sites, and garnets exhibit a wide range of useful properties, including ferrimagnetism and ion transport. However, there have been few reports of the synthesis or properties of garnet superlattices, with layer thicknesses approaching the unit cell dimension of 1.2 nm. Here, we describe superlattices made from Bi and rare earth (RE = Tm, Tb, Eu, Lu) iron garnets (IGs) grown by pulsed laser deposition. Atom probe tomography and transmission electron microscopy reveal the composition modulation without dislocations and layer thicknesses as low as 0.45 nm, less than half a unit cell. TmIG/TbIG superlattices exhibit perpendicular magnetic anisotropy that is qualitatively different from the in-plane anisotropy of the solid solution, and BiIG/LuIG superlattices exhibit ferromagnetic resonance linewidth characteristics of the end-members rather than the solid solution. Garnet superlattices provide a playground for exploring interface physics within the vast parameter space of cation coordination and substitution.