Conventional Pulsed Laser Deposition Research Articles

Temperature dependence of crystalline quality in MgGa2O4 films by oxygen radicals-assisted pulsed laser deposition

This study investigates the growth of MgGa2O4 films using oxygen radicals-assisted pulsed laser deposition (PLD). By changing the substrate temperature from 100 to 500 °C, the structural and optical properties of the films was explored. X-ray diffraction analysis demonstrates that (111) oriented MgGa2O4 films can achieve enhanced crystalline quality by using oxygen radicals compared to films deposited by conventional PLD without plasma. At room temperature transmittance spectra exhibit high transmittance levels across the infrared, visible, and UV regions, with direct bandgaps of approximately 5.4 eV for all deposited samples. These findings underscore the efficacy of oxygen radicals-assisted PLD for the deposition of high-quality MgGa2O4 films at low temperature, thereby expanding the potential applications in advanced electronic and optoelectronic devices compatible with established Si-based integrated circuits.

NaCl flux growth of non-polar m-plane ZnO epitaxial thin film on c-plane sapphire substrate

We have developed a technique to fabricate non-polar m-plane ZnO thin films: the post NaCl flux treatment of Zn-containing precursors, such as amorphous zinc carbonate hydroxide, Zn5(CO3)2(OH)6. Conventionally, single-crystal m-plane sapphire or MgO (001) substrates have been utilized to fabricate m-plane ZnO thin films. In contrast, this method facilitates the growth of m-plane ZnO thin films on various substrates, such as sapphire and quartz glass, despite its c-plane growth habit. Furthermore, the m-plane ZnO thin film was demonstrated to epitaxially grow even on a c-plane sapphire substrate. Owing to the good lattice matching with the substrate, the m-plane ZnO epitaxial film had high crystallinity comparable to a c-plane ZnO epitaxial film that was created using a conventional pulsed laser deposition method, and exhibited similar photocatalytic activity to the c-plane ZnO film. This research offers valuable insights into the fundamental mechanisms of flux growth orientation control, which can be beneficial in designing ZnO-based electronic devices and photocatalysts.

Enhanced performances of a-IGZO TFTs with oxide passivation layers fabricated by hollow cathode assisted PLD

Pulsed laser deposition (PLD) and two-step thermal annealing are combined to fabricate MgO, TiO2, Y2O3, Al2O3, ZrO2 and HfO2 passivation layers on a-IGZO TFTs. The influences of the passivation layers on the electrical properties are investigated. It is found that conventional PLD is sufficient to deposit high-quality Y2O3 and ZrO2 passivation layers, but hollow cathode assisted PLD (HC-PLD) should be employed to solve the oxygen deficiency in MgO, TiO2, Al2O3, and HfO2 thin films by oxygen plasma. Furthermore, two-step annealing is adopted to improve the performances of the devices: Firstly, a-IGZO thin films are pre-annealed to enhance the carrier mobility. Secondly, the passivation layers are deposited on a-IGZO and the whole structures are post-annealed to endow the good on-off performance. The sharp a-IGZO/passivation interfaces remain after thermal annealing. The Hall mobility is mainly restricted by the scattering of metal ions at the a-IGZO/passivation interface. TiO2 passivated devices exhibit the highest Hall mobility of 16.7 cm2V−1s−1, owing to the smaller cation charge. The threshold voltage stability under positive gate bias is dependent on the metal-oxygen bond strength in the passivation layers. ZrO2 passivated devices have the lowest threshold voltage shift, beneficial from the strong Zr-O bonds. The subthreshold performance and the stability under illumination are determined by the oxygen vacancies at a-IGZO/passivation interfaces and ZrO2 passivated devices exhibit the lowest subthreshold swing and the best illumination stability.

Nanosecond laser irradiation of Yttria stabilized Zirconia: Pulsed laser ablation and surface treatment

Nanosecond pulsed laser irradiation resulting in material ablation and surface micro structuring of Yttria Stabilized Zirconia (YSZ) targets, has been investigated. Our study aims to evaluate suitable ablation conditions enabling either, creation of desired YSZ surfaces having micro porosity for directed use, or generation of YSZ vapors for deposition of homogenous, dense and particle free YSZ films via conventional Pulsed Laser Deposition (PLD) technique. The work being reported here involves a thermal model based theoretical simulation describing heat transport, melting and vaporization of a laser irradiated YSZ target. Our simulation has been validated against our experimental data on nanosecond laser ablation from a sample target of ceramic YSZ. Surface porosity generated on laser irradiated YSZ targets for low laser fluence levels ∼ 1 ​J/cm2 has been explained in terms of pore formation via entrapment of gas bubbles in the solidifying interface on laser melting and re-solidification thereafter, of the YSZ target. To understand surface crater formation on laser irradiated YSZ targets at high laser fluence levels ∼10 ​J/cm2 maximum temperature reached by the laser irradiated YSZ target has been compared with the thermodynamic critical temperature of YSZ. Our study confirms that judicious choice of laser fluence enables either, creation of surfaces having micro porosity of desired nature on YSZ target, or controlled generation of YSZ vapors for deposition of good quality YSZ films and coatings using laser deposition technique.

Alternate-Target Layer-By-Layer Pulsed Laser Deposition of Epitaxial BiVO4 Thin Films

Bismuth vanadate (BiVO4) has emerged as one of the highest performing metal oxide photoelectrodes for solar energy-to-fuels applications [1, 2]. This achievement has been largely attributed to the development of high-quality synthesis techniques. Specifically, epitaxial synthetic routes to producing lattice-matched, near single-crystalline quality BiVO4 with minimal extrinsic defects have been essential to understand the fundamental and PEC properties of BiVO4 that are inaccessible by conventional bulk synthesis techniques. In addition, epitaxial synthesis may also be employed as a strategy to further improve the PEC properties of BiVO4 through, for instance, altering the band structure and enhancing the carrier dynamics by strain engineering. Hence, the ability to produce high-quality single-phase epitaxial BiVO4 films is desirable.To date, molecular beam epitaxy (MBE), chemical vapor deposition (CVD), and pulsed laser deposition (PLD) [3] have been used to fabricate epitaxial BiVO4 thin films, with PLD having the advantage of relatively simple experimental setup and material versatility. However, an oft-noted drawback in conventional PLD using single oxide targets is off-stoichiometry in the deposited films; this is especially so for BiVO4 which requires a Bi-rich compound target to achieve a stoichiometric BiVO4 film [4]. This problem is also expected in general for multinary oxides composed of elements with very different ablation properties. To alleviate the limitations of conventional PLD, we employ for the first time alternate-target layer-by-layer PLD as a more elegant approach to produce high quality epitaxial BiVO4 films. Briefly, constituent oxide targets are alternately ablated by an excimer laser (λ= 248 nm) to build the desired film one unit cell thick at a time. Stoichiometry is controlled by the number of shots corresponding to a specified laser fluence for the constituent oxide target.To demonstrate the method, we deposited epitaxial BiVO4 films onto (001)-oriented yttrium-stabilized zirconia (YSZ) using 4N-pure Bi2O3 and V2O5 targets. Films grown are single phase BiVO4 as shown by x-ray diffraction. Out-of-plane diffraction peaks indexed to BiVO4(00l) suggests epitaxy of the film onto the substrate; reciprocal space maps of the asymmetric BiVO4(208) and YSZ(204) peaks further confirm the BiVO4(001) || YSZ(001) epitaxial relationship (top figure). Rocking curves of the BiVO4 (004) peak (FWHM ~ 0.015-0.041) indicate high crystalline perfection of the BiVO4 film, almost approaching that of the YSZ substrate (FWHM ~ 0.010). Thickness dependent-rocking curve studies reveal that BiVO4 films are strained to the substrate for film thicknesses under 22 nm; above this critical thickness, film relaxation ensues. In turn, the resulting optoelectronic properties of the BiVO4 film is dictated by its relaxation state. The optical band gap narrows with film relaxation as observed with spectroscopic ellipsometry. Moreover, steady-state photoluminescence emission spectroscopy reveals a sub-bandgap state (A 2, bottom figure) associated with strained BiVO4 films, on top of a state consistent with band-to-band recombination (B1 ). A higher energy sub-bandgap state (A 1, bottom figure) develops as the film relaxes. The implications of the relaxation state on the charge carrier dynamics and photoelectrochemical properties of BiVO4 will be discussed. Figure: (top) reciprocal space maps of the asymmetric BiVO4(208) and YSZ(204) peaks; (bottom) photoluminescence emission spectra of strained and relaxed BiVO4 films.

Strong Interfacial Coupling of Tunable Ni-NiO Nanocomposite Thin Films Formed by Self-Decomposition.

The next-generation spintronic devices including memristors, tunneling devices, or stochastic switching exert surging demands on magnetic nanostructures with novel coupling schemes. Taking advantage of a phase decomposition mechanism, a unique Ni-NiO nanocomposite has been demonstrated using a conventional pulsed laser deposition technique. Ni nanodomains are segregated from NiO and exhibit as faceted "emerald-cut" morphologies with tunable dimensions affected by the growth temperature. The sharp interfacial transition between ferromagnetic (002) Ni and antiferromagnetic (002) NiO, as characterized by high-resolution transmission electron microscopy, introduces a strong exchange bias effect and magneto-optical coupling at room temperature. In situ heating-cooling X-ray diffraction (XRD) study confirms an irreversible phase transformation between Ni and NiO under ambient atmosphere. Synthesizing highly functional two-phase nanocomposites with a simple bottom-up self-assembly via such a phase decomposition mechanism presents advantages in terms of epitaxial quality, surface coverage, interfacial coupling, and tunable nanomagnetism, which are valuable for new spintronic device implementation.

Study of titanium nitride film growth by plasma enhanced pulsed laser deposition at different experimental conditions

In this work, we have combined a conventional pulsed laser deposition (PLD) system with a dual radio frequency (RF) discharge to create a plasma-enhanced PLD system, known as (PE-PLD). This system was used to grow titanium nitride (TiN) thin films in order to study the feasibility of obtaining control over the nitrogen concentration and the deposition rate. The characterization of the RF plasma was performed using an RF compensated Langmuir probe, while atomic force microscopy (AFM), optical profilometry, Raman spectroscopy, and x-ray diffraction (XRD) were used to analyze the deposited thin films. We observed a significantly enhanced nitrogen concentration and deposition rate as a function of the RF plasma parameters, substrate temperature, and deposition time. Furthermore, we have observed that, using a dual RF configuration, it becomes possible to modify independently the flow and the bombardment energy of the nitrogen ions that impact the substrate. These means allow the control of the nitrogen concentration and deposition rate.

Optical properties of Si nanocrystals in SiO2 matrix synthesized by reactive pulsed laser deposition

Si ion implantation into SiO2 is widely used to synthesize specimens of SiO2 containing supersaturated Si. We also prepared specimens of supersaturated Si in SiO2 by reactive pulsed laser deposition (PLD) in an oxygen atmosphere. After high temperature annealing of these specimens induces the formation of embedded luminescent Si nanocrystals in SiO2. In this work, the potentialities of excimer UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing (RTA) to enhance the photoluminescence and to achieve low temperature formation of Si nanocrystals have been investigated. The Si ions were introduced at acceleration energy of 180 keV to fluence of 7.5 x 1016 ions/cm2. We also prepared Si nanocrystals embedded in a SiO2 by reactive pulsed laser deposition (PLD) in an oxygen atmosphere by using conventional PLD system with 2nd-harmonic YAG laser (532 nm, 10 Hz, 80 J/cm2) under controlled low oxygen pressure. Samples were subsequently irradiated with an excimer-UV lamp. After the process, the samples were rapidly thermal annealed before furnace annealing (FA). Photoluminescence spectra were measured at various stages at the process. We found that the luminescence intensity is enhanced with excimer-UV irradiation and RTA. Moreover, effective visible photoluminescence is found to be observed even after FA below the annealing temperature at 1000 °C, only for specimens treated with excimer-UV lamp and RTA. We will make clear the similarities of photoluminescence with the way of preparation techniques.

Preparation of two-dimensional thin films by backside irradiation pulsed laser deposition method using powder target

In this work, two-dimensional thin films were prepared by pulsed laser deposition (PLD) via backside irradiation. For this, a handmade transparent target holder made of quartz-glass was used to hold the powder targets. Visible-wavelength pulsed laser irradiation was applied from the holder side to the substrate. Using this new method, indium (In) and zinc (Zn)-concentrated thin films were prepared on a silicon substrate. The deposition rate of the film prepared with this method was calculated from the thickest position of the prepared film and the deposition time. The deposition rate was lower than for films prepared via conventional PLD. Two-dimensional profiles of the prepared films via backside irradiation PLD displayed a convex shape and its spatial resolution strongly depended on the laser profile. X-ray photoelectron spectroscopy measurements suggested that tailored In and Zn composition thin films could be prepared with this method using an In2O3 and ZnO powder target.

Pulsed laser deposition with rapid beam deflection by a galvanometer mirror scanner.

A pulsed laser deposition system with rapid beam deflection (RBD-PLD) by a galvanometer mirror scanner has been developed for alternating ablation of multiple targets with a single laser instrument. In this system, the alternating deposition of different target materials is carried out by scanning the laser beam between the positionally fixed targets with a galvanometer mirror instead of mechanically switching the target positions on a fixed optical path of the laser beam as is done in conventional pulsed laser deposition (PLD) systems. Thus, the "wait" time required for switching target materials to be deposited, which typically takes several seconds in a conventional system, can be made as short as a few milliseconds. We demonstrate some of the advantages of this PLD system in several technologically important aspects of thin film synthesis: (1) fast fabrication of binary alloy films, (2) preparation of natural composition spread libraries, (3) effect of the target switching time on the deposition of volatile compounds, (4) control of the degree of mixing of two different materials in a film, and (5) efficient growth of compositionally graded thin films.

Terahertz time domain spectroscopy of GdBCO superconducting thin films

We present terahertz optical properties of GdBa2Cu3O7-x (GdBCO) superconducting thin films. GdBCO films with a thickness of about 105 nm were grown on a LaAlO3 (LAO) single crystal substrate using a conventional pulsed laser deposition (PLD) technique. Using an Ar ion milling system, the thickness of the GdBCO film was reduced to 58 nm, and its surface was also smoothened. Terahertz (THz) transmission spectra through two different GdBCO films are measured over the range between 0.2 and 1.5 THz using THz time domain spectroscopy. Interestingly, the THz transmission of the thinner GdBCO film has been increased to six times larger than that of the thicker one, while the thinner film is still maintaining its superconducting property at below 90 K.

Combinatorial Material Science and Strain Engineering Enabled by Pulsed Laser Deposition Using Radially Segmented Targets.

Vertical composition gradients of ternary alloy thin films find applications in numerous device structures. Up to now such gradients along the growth direction have not been realized by standard pulsed laser deposition (PLD) systems. In this study, we propose an approach based on a single elliptically segmented PLD target suited for the epitaxial growth of vertically graded layers. The composition of the thin films can be varied by a simple adjustment of the position of the PLD laser spot on the target surface. We demonstrate this principle for the Mg xZn1- xO alloy system. Such vertically composition-graded Mg xZn1- xO thin films exhibit high optical quality and a well-defined Mg-content for each layer. No signs of interdiffusion of Mg-atoms between the layers have been found. Further, this method is capable to deposit homogeneous thin films with any desired, well-defined cation composition having the same high optical and structural quality as films grown by conventional PLD.

Growth of antiperovskite oxide Ca3SnO films by pulsed laser deposition

We report the epitaxial growth of Ca3SnO antiperovskite oxide films on (0 0 1)-oriented cubic yttria-stabilized zirconia (YSZ) substrates by using a conventional pulsed laser deposition (PLD) technique. In this work, a sintered Ca3SnO pellet is used as the ablation target. X-ray diffraction measurements demonstrate the (0 0 1) growth of Ca3SnO films with the antiperovskite structure and a cube-on-cube orientation relationship to the YSZ substrate. The successful synthesis of the antiperovskite phase is further confirmed by X-ray photoemission spectroscopy. These results strongly suggest that antiperovskite-oxide films can be directly grown on substrates from the target material using a PLD technique.

Preparation of low roughness CZTS thin film and solar cell by SMPLD method

To solve the problems of high roughness and defects on the surface of thin film prepared by the conventional pulsed laser deposition method (PLD), the optimized shadow masked pulsed laser deposition method (SMPLD) was proposed in this work to prepare the copper zinc tin sulfur (CZTS) thin film. Comparative analysis was carried out on the CZTS thin films and solar cells prepared by these two PLD methods. The film prepared by SMPLD is compact and even, and the surface roughness decreases by one order of magnitude. The efficiency of the CZTS thin film solar cell prepared by SMPLD is approximately 4.4%. This value is 1.3% higher than that prepared by the conventional PLD method.

Fabrication and Characterization of Two-Dimensional Layered MoS2 Thin Films by Pulsed Laser Deposition

Direct growth of uniform wafer-scale two-dimensional (2D) layered materials using a universal method is of vital importance for utilizing 2D layers into practical applications. Here, we report on the structural and transport properties of large-scale few-layer MoS2 back-gated field effect transistors (FETs), fabricated using conventional pulsed laser deposition (PLD) technique. Raman spectroscopy and transmission electron microscopy results confirmed that the obtained MoS2 layers on SiO2/Si substrate are multilayers. The FETs devices exhibit a relative high on/off ratio of 5 × 102 and mobility of 0.124 cm2V−1S−1. Our results suggest that the PLD would be a suitable pathway to grow 2D layers for future industrial device applications.

Combined magnetron sputtering and pulsed laser deposition of TiO2 and BFCO thin films

We report the successful demonstration of a hybrid system that combines pulsed laser deposition (PLD) and magnetron sputtering (MS) to deposit high quality thin films. The PLD and MS simultaneously use the same target, leading to an enhanced deposition rate. The performance of this technique is demonstrated through the deposition of titanium dioxide and bismuth-based perovskite oxide Bi2FeCrO6 (BFCO) thin films on Si(100) and LaAlO3 (LAO) (100). These specific oxides were chosen due to their functionalities, such as multiferroic and photovoltaic properties (BFCO) and photocatalysis (TiO2). We compare films deposited by conventional PLD, MS and PLD combined with MS, and show that under all conditions the latter technique offers an increased deposition rate (+50%) and produces films denser (+20%) than those produced by MS or PLD alone, and without the large clusters found in the PLD-deposited films. Under optimized conditions, the hybrid technique produces films that are two times smoother than either technique alone.

Pulsed laser deposition of plasmonic nanostructured gold on flexible transparent polymers at atmospheric pressure

In this paper, we outline a novel technique for the deposition of nanostructured thin films utilizing a modified form of pulsed laser deposition (PLD). We demonstrate confined atmospheric PLD (CAP) for the deposition of gold on cyclic olefin polymer substrates. The deposition process is a simplified form of conventional PLD, with deposition conducted under atmospheric conditions and the substrate and target in close proximity. It was found that this confinement results in the deposition of nanostructured thin films on the substrate. Infrared spectroscopy showed no significant change of polymer surface chemistry as a result of the deposition process, and optical spectroscopy revealed plasmonic behavior of the resulting thin film. The effect of laser fluence on the deposition process was also examined with more uniform films deposited at higher fluences.

Selective growth of epitaxial Sr2IrO4 by controlling plume dimensions in pulsed laser deposition

We report that epitaxial Sr2IrO4 thin-films can be selectively grown using pulsed laser deposition (PLD). Due to the competition between the Ruddlesden-Popper phases of strontium iridates (Srn+1IrnO3n+1), conventional PLD methods often result in mixed phases of Sr2IrO4 (n = 1), Sr3Ir2O7 (n = 2), and SrIrO3 (n = ∞). We have discovered that reduced PLD plume dimensions and slow deposition rates are the key for stabilizing pure Sr2IrO4 phase thin-films, identified by real-time in-situ monitoring of their optical spectra. The slow film deposition results in a thermodynamically stable TiO2\\SrO\IrO2\SrO\SrO configuration at an interface rather than TiO2\\SrO\SrO\IrO2\SrO between a TiO2-terminated SrTiO3 substrate and a Sr2IrO4 thin film, which is consistent with other layered oxides grown by molecular beam epitaxy. Our approach provides an effective method for using PLD to achieve pure phase thin-films of layered materials that are susceptible to several energetically competing phases.

Superconducting Properties in SmBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> Films With High Density of BaHfO<sub>3</sub> Nanorods Fabricated With a Seed Layer

A high density of BaMO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (BMO) nanorods within a REBa <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">y</sub> (REBCO) film can be generated by heavy doping of the BMO. This is very effective in improving superconducting properties in high magnetic fields. However, heavy doping causes a significant T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> reduction. Introduction of a high density of BMO nanorods into REBCO films without reduction in T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> is required. To this end, we deposited SmBa <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">y</sub> (SmBCO) films with various amount of BaHfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (BHO) by a pulsed laser deposition (PLD) method using a seed-layer technique and a low-temperature growth (LTG) technique. Using this technique, we can fabricate a purely c-axis-oriented SmBCO film even at low substrate temperatures T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> . The SmBCO films with BHO were fabricated at low T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> of 750 °C without heavy doping of BHO. As a result, the BHO nanorods became thinner and denser than those within SmBCO films fabricated by conventional PLD methods at high T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> . The maximum density was 4780/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">φ</sub> of the film reached 9.9 T. These samples showed high T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> (> 90 K). We have therefore successfully fabricated high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> SmBCO films with high densities of BHO nanorods using the LTG technique.

Oxygen-radical-assisted pulsed-laser deposition of β-Ga2O3 and β-(AlxGa1−x)2O3 films

We report on impacts of oxygen-radical (O⁎) atmosphere for pulsed-laser deposition (PLD) of β-Ga2O3 and β-(AlxGa1−x)2O3 films on (010) β-Ga2O3 substrate in comparison with conventional PLD in O2 atmosphere. Severe sublimation of Ga species arising from insufficient oxidation in the O2 atmosphere resulted in substantial decrease in growth rate of the homoepitaxial films and condensation of Al content in the (AlxGa1−x)2O3 films. In the case of O⁎-assisted PLD, it was found that the growth rate of homoepitaxial films greatly recovered, and the Al content remained nearly identical to that in the target. Moreover, the use of O⁎ allowed to reduce surface roughness of homoepitaxial films. These results indicate that O⁎-assisted PLD is a powerful tool for fabricating β-Ga2O3-based heterostructures.