Influence Of Oxygen Pressure Research Articles

High responsivity and detectivity β-Ga2O3 solar-blind photodetectors optimized by oxygen vacancy engineering

Solar-blind photodetectors (SBPDs) are core essential components for many critical applications such as precision guidance, fire warning, and space communications. Ultra-wide bandgap semiconductor β-Ga2O3 is considered to be an ideal material for the fabrication of SBPDs. However, synthetizing β-Ga2O3 with high quality factor while simultaneously in situ modulation of electronic and optoelectronic properties to enhance performance has been challenging. Here, pulsed laser deposition (PLD) technology is used to synthesize high-quality β-Ga2O3 thin films on a sapphire substrate. The oxygen vacancy engineered β-Ga2O3 films can achieve in situ precise control of their surface morphology, optical parameters, and optoelectronic properties by simply adjusting the oxygen pressure. Meanwhile, the optimal thickness of the β-Ga2O3 film for the developing high-performance SBPD is ∼221 nm, determined by fitting and analyzing the optical parameters measured by the ellipsometry. Subsequently, the influence of oxygen pressure on the performance of β-Ga2O3 SBPD is thoroughly explored, considering the optimization of electrode size and deposition time. When the oxygen pressure is set to 15 Pa, the β-Ga2O3-based SBPD achieves highly competitive responsivity (R) and detectivity (D*) at 250 nm, with values of 1080 A·W−1 and 1.4 × 1016 cm·W−1·Hz1/2, respectively. Additionally, the noise component of the β-Ga2O3 SBPD is further studied to calibrated the traditional device performance results. This work introduces a simple and straightforward approach to in situ tuning of the optoelectronic properties of β-Ga2O3, which is important for advancing β-Ga2O3 film growth technology and fabricating high-performance photodetectors.

Influence of oxygen pressure on the ferroelectricity of pulsed laser deposition fabricated epitaxial Y-doped HfO2

Ferroelectric properties of hafnium-based thin films have gained significant interest, yet the fundamental mechanisms responsible for the emergence of the ferroelectric phase continue to be inadequately investigated. In contrast with polycrystalline films fabricated by atomic layer deposition or sputter methods, which possess uncertainty in polarization orientation, epitaxial ferroelectric HfO2-based materials are less investigated, especially for factors such as electric field and oxygen vacancy, which are proposed and examined for their potential impacts on phase stability. In this study, Y-doped hafnium oxide (HYO) ferroelectric epitaxial films were fabricated using pulsed laser deposition, with variations in oxygen pressure during the deposition process. Structural and electrical analyses of HYO epitaxial ferroelectric films prepared under differing oxygen pressures revealed a correlation between the ferroelectric properties of the films and the oxygen content. An optimal selection of oxygen pressure was found to be conducive to the formation of HYO epitaxial ferroelectric films, presenting a promising avenue for future ferroelectric memory applications.

Influence of oxygen pressure during deposition on the microwave dielectric tunability of Ba0.5Sr0.5TiO3 thin films in PLD process

Thin films of Ba0.5Sr0.5TiO3 (BSTO) were pulsed laser deposited on platinized silicon substrates with varying oxygen pressure from 5 × 10−1 mbar to 5 × 10−6 mbar. A strong correlation between the oxygen partial pressure during the PLD process and the structural and microwave dielectric properties of the PLD-grown BSTO thin films is observed. The structural properties of the PLD-grown BSTO films were analyzed by XRD, Raman spectroscopy, FTIR spectroscopy, and XPS studies, and it is observed that oxygen vacancies are formed in low oxygen pressure deposited films. Dielectric studies at microwave frequencies show that high oxygen pressure deposited BSTO films show good microwave dielectric properties and crystallinity. At 1 GHz frequency, the BSTO film grown at 5 × 10−2 mbar oxygen pressure exhibits a dielectric constant ∼470 and dielectric loss ∼0.15. The oxygen vacancies change the nature of metal-oxide bonding (Ti-O bond), affect the polarizabilities, and, as a result, reduce the dielectric constant. A maximum dielectric tunability of 71 % is observed in microwave frequencies for the BSTO films grown at 5 × 10−2 mbar oxygen pressure.

Determination of Kinetic Parameters and Identification of the Rate-Determining Steps in the Oxygen Exchange Process for LaNi0.6Fe0.4O3-δ.

The mixed ionic and electronic oxide LaNi0.6Fe0.4O3-δ (LNF) is a promising ceramic cathode material for solid oxide fuel cells. Since the reaction rate of oxygen interaction with the cathode material is extremely important, the present work considers the oxygen exchange mechanism between O2 and LNF oxide. The kinetic dependence of the oxygen/oxide interaction has been determined by two isotopic methods using 18O-labelled oxygen. The application of the isotope exchange with the gas phase equilibrium (IE-GPE) and the pulsed isotope exchange (PIE) has provided information over a wide range of temperatures (350-800 °C) and oxygen pressures (10-200 mbar), as each method has different applicability limits. Applying mathematical models to treat the kinetic relationships, the oxygen exchange rate (rH, atom × cm-2 × s-1) and the diffusion coefficient (D, cm2/s) were calculated. The values of rH and D depend on both temperature and oxygen pressure. The activation energy of the surface exchange rate is 0.73 ± 0.05 eV for the PIE method at 200 mbar, and 0.48 ± 0.02 eV for the IE-GPE method at 10-20 mbar; for the diffusion coefficient, the activation energy equals 0.62 ± 0.01 eV at 10-20 mbar for the IE-GPE method. Differences in the mechanism of oxygen exchange and diffusion on dense and powder samples are observed due to the different microstructure and surface morphology of the samples. The influence of oxygen pressure on the ratio of contributions of different exchange types to the total oxygen exchange rate is demonstrated. For the first time, the rate-determining step in the oxygen exchange process for LNF material has been identified. This paper discusses the reasons for the difference in the mechanisms of oxygen exchange and diffusion.

High-efficient compound sinking machining of Ti6Al4V with the assistance of oxygen

ABSTRACT Arc machining is suitable for efficiently processing typical difficult-to-cut material Ti6Al4V. Traditional arc sinking machining commonly uses water-based dielectric because of its safety and good cooling capacity. However, water-based dielectric generally has high conductivity that causes frequent short circuits and strong electrolytic reactions during machining, thereby reducing machining stability and deteriorating machining performance. This paper proposes a novel high-efficient compound sinking machining that combines arc machining with electrical discharge machining (EDM). The dielectric is formed by dispersing oxygen into deionized water, thus reducing the shortcomings of traditional water-based dielectric and introducing the advantages of gas-based one. The feasibility of the proposed method is systematically studied compared to the method that uses deionized water. Influences of oxygen pressure, pulse duration, and peak current are investigated. Characteristics of surface topography and recast layer are also studied. Results suggest that the properties of dielectric improve, and the machining stability and machining intensity increase with the assistance of oxygen. Therefore, compared with using deionized water, the proposed method shows better processing characteristics, including larger material removal rate (MRR), smaller relative electrode wear rate (REWR), and thinner recast layers. The proposed method is promising to process Ti6Al4V due to its high efficiency and environment-friendly properties.

Influence of Oxygen Pressure on Heterogeneous Equilibria in the R–Mn–O (R = Y, Ho–Lu) R–Mn–O (R = Y, Ho–Lu) Complex Oxide Systems

Influence of Oxygen Pressure on Heterogeneous Equilibria in the R–Mn–O (R = Y, Ho–Lu) R–Mn–O (R = Y, Ho–Lu) Complex Oxide Systems

Effect of oxygen partial pressure on microstructure, optical and electrical property of C-Al co-doped ZnO films

C-Al co-doped ZnO films with superior optical and electrical property have been deposited at oxygen partial pressure range 1–7 Pa by pulse laser deposition. The influences of oxygen pressure on crystalline, optical and electrical property have been investigated. The C-Al co-doped ZnO films exhibit a superior crystallinity and greater grain size in the range of 1 Pa–3 Pa compared to AZO films. Furthermore, carbon doping at various oxygen partial pressure significantly improves the optical and electrical property. C-Al co-doped ZnO film reaches the lowest resistivity of 3.1×10-4 Ω cm at 1 Pa. The average transmittance is higher than 85% and attains the optimal value of 89.9 %.

Influence of Oxygen Pressure on Switching in Memoristors Based on Electromoformed Open Sandwich Structures

Samples of nonvolatile electrically reprogrammable memory elements (memristors) based on electroformed TiN–TiO2–SiO2–W open sandwich structures, made using thin-film technology, are studied. A technique is developed and experimental studies are performed of the effect of oxygen pressure over the surface of the insulating gap of structures and the current limiting mode during the action of a switching pulse from a low to a highly conductive state on the characteristics of memory elements. The existence of a threshold value of oxygen pressure at which switching stops and its dependence on the value of the limiting current are shown. An interpretation of the experimental results based on the ideas developed on the mechanisms of the processes of the formation and disappearance of particles of the conducting phase in the insulating gap of an electroformed structure is presented.

Island growth mode in pulsed laser deposited ferroelectric BaTiO3 thin films: The role of oxygen pressure during deposition

Pulsed laser deposition is widely used to grow BaTiO3 thin films. We investigated the influence of oxygen pressure during growth on the topography, microstructure, and roughness of ferroelectric epitaxial BaTiO3 thin films. It also presented an analysis of the epitaxial growth mode and defects throughout the film thickness using aberration-corrected transmission electron microscopy. Although ferroelastic (twin boundary) domain walls are absent, several misfit dislocations were observed and might be the primary cause of the observed island growth mode.

Influence of oxygen pressure on the electrical properties of Mn-doped Bi0.5Na0.5TiO3BaTiO3 thin films by pulsed laser deposition

Ferroelectric Mn-doped 0.935Bi 0.5 Na 0.5 TiO 3 -0.065BaTiO 3 (MnBNBT) thin films were fabricated on (111)Pt/Ti/SiO 2 /Si substrates via pulsed laser deposition under different oxygen pressures. (100)-preferred orientation and dense films with perovskite structure were grown. The MnBNBT thin film deposited at an optimized oxygen pressure of 25 Pa exhibited a well-defined ferroelectric P - E loop with an average remnant polarization P r of 27 μC/cm 2 , a coercive field E c of 5.7 kV/mm, and a high relative dielectric constant of 1295. The leakage current characteristics were assessed, demonstrating that the ohmic conduction behaviors and Fowler-Nordheim tunneling were the main mechanisms of the MnBNBT thin films. Piezoelectric force microscopy indicated that the MnBNBT films possessed favorable local piezoelectric responses and multidomain states. The results suggest that the lead-free thin film produced is potentially applicable in ferroelectric and piezoelectric devices.

Nonstoichiometry Driven Ferromagnetism in Double Perovskite La2Ni1–xMn1+xO6 Insulating Thin Films

In this work we report on the epitaxial growth of La2NiMnO6 double perovskite thin films on top of (001) oriented SrTiO3 substrates by RF magnetron sputtering. The influence of oxygen pressure (PO2) and growth temperature on the microstructure, stoichiometry of the films, and magnetic and transport properties is thoroughly investigated. It is found that high oxygen pressure promotes the growth of stoichiometric films, with a Ni/Mn ratio almost equal to 1. However, these films exhibit poor ferromagnetic properties with respect to the expected optimum values corresponding to ferromagnetic ordering mediated by superexchange interaction between Mn4+ and Ni2+ according to the Goodenough-Kanamori rules. Most interestingly, films grown at low PO2 exhibit Ni/Mn ratios below 1, but ferromagnetic properties close to the optimal ones. The valence balance between Ni and Mn ions in nonstoichiometric sample has been elucidated by X-ray absorption spectroscopy. The results indicate that Ni deficiency plays a crucial rol...

Influence of oxygen pressure on the fs laser-induced oxidation of molybdenum thin films

We present a study of femtosecond (1028 nm, 230 fs, 54.7 MHz) laser processing on molybdenum (Mo) thin films. Irradiations were done under ambient air as well as pure oxygen (O2) at various gauge pressures (4, 8, 12 and 16 psi). Our results indicate that the high heating rates associated with laser processing allow the production of different molybdenum oxides. Raman spectroscopy and scanning electron microscopy are used to characterize the molybdenum oxidation for the different irradiation and oxygen pressures parameters chosen showing a high correlation between well-defined oxidation zones and the oxygen pressure surrounding the samples during the irradiation of the Mo thin films.

沉积氧压对二氧化钒薄膜结构、光电性能及其MIT相变特性的影响研究

沉积氧压对二氧化钒薄膜结构、光电性能及其MIT相变特性的影响研究

氧压变化对脉冲激光沉积法制备BeMgZnO四元合金薄膜性能的影响

氧压变化对脉冲激光沉积法制备BeMgZnO四元合金薄膜性能的影响

Influence of Oxygen Pressure on the Domain Dynamics and Local Electrical Properties of BiFe0.95Mn0.05O₃ Thin Films Studied by Piezoresponse Force Microscopy and Conductive Atomic Force Microscopy.

In this work, we have studied the microstructures, nanodomains, polarization preservation behaviors, and electrical properties of BiFe0.95Mn0.05O3 (BFMO) multiferroic thin films, which have been epitaxially created on the substrates of SrRuO3, SrTiO3, and TiN-buffered (001)-oriented Si at different oxygen pressures via piezoresponse force microscopy and conductive atomic force microscopy. We found that the pure phase state, inhomogeneous piezoresponse force microscopy (PFM) response, low leakage current with unidirectional diode-like properties, and orientation-dependent polarization reversal properties were found in BFMO thin films deposited at low oxygen pressure. Meanwhile, these films under high oxygen pressures resulted in impurities in the secondary phase in BFMO films, which caused a greater leakage that hindered the polarization preservation capability. Thus, this shows the important impact of the oxygen pressure on modulating the physical effects of BFMO films.

Influence of Oxygen Concentration on Plasma Dynamic Synthesis Product in Fe-O System

In spite of being known for centuries, iron oxides are still important. Such modifications as magnetite Fe3O4 and epsilon phase ε-Fe2O3 are of great scientific and practical interest due to their promising electromagnetic properties. Nonetheless, only few methods allow synthesizing both of these phases, but they have some well-known disadvantages, which limit the possibility of using them widely. This work shows a unique method of synthesizing these materials in one short-duration plasma dynamic process using a coaxial magnetoplasma accelerator with iron electrode system. The plasma chemical reaction occurs between the iron-containing plasma and gaseous precursor (oxygen). The influence of oxygen pressure on the products of plasma dynamic synthesis was also studied in the framework of this investigation. It was found that the higher oxygen concentration leads to the formation of product with predominant content of epsilon iron oxide ε-Fe2O3, as well as lower oxygen concentration results in obtaining the product with the dominance of magnetite phase.

Influence of oxygen pressure on microstructure and dielectric properties of lead-free BaTi0.85Sn0.15O3 thin films prepared by pulsed laser deposition

Lead-free barium tin titanate BaTi0.85Sn0.15O3 (BTS) ferroelectric thin films have been deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. The structure and dielectric properties of thin films deposited at various oxygen pressures are investigated systematically. By optimizing the oxygen pressure during the deposition, the structure and dielectric properties are improved. The thin films grown at 15Pa have the best crystal quality and the largest grain size, which result in the enhancement of the dielectric properties. The dielectric constant and loss tangent show the similar trend in the entire oxygen pressure range. The influence mechanisms of the oxygen pressure on the structure and dielectric properties are proposed. The BTS thin films deposited at 15Pa with large figure of merit (FOM) of 81.1, high tunability of 72.1%, moderate dielectric constant of 341, low loss tangent of 0.009 are considered to be appropriate as a field tunable ferroelectric material for electrically tunable devices.

Influence of oxygen pressure on the structural and electrical properties of CuO thin films prepared by pulsed laser deposition

CuO thin films were deposited on glass substrates by pulsed laser deposition (PLD) and the influence of oxygen (O2) pressure on the structural and electrical properties of the CuO films was studied. X-ray diffraction (XRD) measurements reveal that the films deposited at 3×10−3Pa, 3–5Pa, and 8–12Pa show a single Cu2O phase, mixed Cu2O–CuO phase, and single CuO phase, respectively. The preferential orientation of CuO films varies from (111) to (002) as the O2 pressure increases from 5 to 8Pa. Hall effect measurements and gas-sensing property study demonstrate that CuO films deposited at 3–5Pa show p-type conductivity while those deposited at 8–12Pa show n-type conductivity. The CuO film deposited at 5Pa has the highest carrier concentration of 5.0×1017cm−3 and the lowest resistivity of 9.5×101Ωcm.

Local Piezoresponse and Electrical Behavior of Multiferroic BiFe0.95Mn0.05O3 Epitaxial Thin Films Deposited Under Different Oxygen Pressure

Multiferroic BiFe0.95Mn0.05O3 (BFMO) epitaxial thin films were grown on SrRuO3, SrTiO3 and TiN-buffered (001)-oriented Si substrates under different oxygen pressure by pulsed laser deposition. The influence of oxygen pressure on the microstructures, domain configurations and their local piezoresponse and electrical behaviors were investigated by the piezoresponse force microcopy and conductive atomic force microscopy. BFMO thin film at low oxygen pressure was found to demonstrate pure phase state, inhomogeneous piezoresponse and low leakage behavior with diode-like behavior, while high oxygen pressure leads to impurity Bi2O3 phase-enclosed BFMO films with higher leakage current above 2 nA, revealing the importance of the oxygen pressure in governing the physical properties of BFMO films.

The Influence of Oxygen Pressure on ZnO:Al Thin Films Properties Grown by Layer by Layer Growth Method at Magnetron Sputtering

The influence of oxygen pressure in the deposition chamber on the structure, morphology, optical and electrical properties of aluminum doped ZnO films deposited by a layer by layer growth method in magnetron sputtering on glass substrates was studied. The effect of the application of the traditional one-step approach and our proposed layer by layer growth method in magnetron sputtering on the properties of doped by aluminum ZnO films was analyzed. It is found that with decreasing oxygen pressure in the deposition chamber improves the structure, increases transmittance in the visible spectrum of radiation and decreases resistivity of ZnO:Al films. It is shown that the application of layer by layer growth method in magnetron sputtering allows to grow the transparent conductive ZnO:Al films with higher performance parameters, compared with the films which condensed by traditional approach in magnetron sputtering. The layer by layer growth method allows to grown ZnO:Al films with electrical resistance at 6.1·10-4 Ohm·cm and transmission in the visible light of 95%, which is promising for their aplication in photovoltaic devices.