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Development of a scanning probe microscopy integrated atomic layer deposition system for <i>in situ</i> successive monitoring of thin film growth
摘要： A dual chamber system integrated with atomic layer deposition (ALD) and atomic force microscopy (AFM) was developed for the successive monitoring of nanoparticles to thin film growth process. The samples were fabricated in the ALD chamber. A magnetic transmission rod enabled sample transferring between the ALD and the AFM test chambers without breaking the vacuum, avoiding possible surface morphology change when frequently varying the growth condition and oxidation under ambient condition. The sample transmission also avoids deposition and contamination on the AFM tip during the successive testing. The sample stage has machined a group of accurate location pinholes, ensuring the 10 μm2 measurement consistency. As a demonstration, the platinum thin films with different thickness were fabricated by varying ALD cycles. The surface morphology was monitored successively during the deposition. Under vacuum with controlled oxygen partial pressure, the aging and sintering phenomenon of particles has been studied in the AFM testing chamber after high temperature treatment. The integrated AFM/ALD instrument is potentially a powerful system for monitoring the thin film preparation and characterization.
关键词： platinum thin films,atomic force microscopy,in situ monitoring,atomic layer deposition,thin film growth
更新于2025-09-04 15:30:14
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SWIR-LWIR Photoluminescence from Sb-based Epilayers Grown on GaAs Substrates by using MBE
摘要： Utilizing Sb-based bulk epilayers on large-scale low-cost substrates such as GaAs for fabricating infrared (IR) photodetectors is presently attracting significant attention worldwide. For this study, three sample series of GaAsxSb1?x, In1?xGaxSb, and InAsxSb1?x with different compositions were grown on semi-insulating GaAs substrates by using molecular beam epitaxy (MBE) and appropriate InAs quantum dots (QDs) as a defect-reduction buffer layer. Photoluminescence (PL) signals from these samples were observed over a wide IR wavelength range from 2 μm to 12 μm in agreement with the expected bandgap, including bowing effects. In particular, interband PL signals from InAsxSb1?x and In1?xGaxSb samples even at room temperature show promising potential for IR photodetector applications.
关键词： SWIR,LWIR,IR detector,MWIR,Sb-based thin films
更新于2025-09-04 15:30:14
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Preparation of ZnO Nanoparticles Under Ultrasonic Irradiation and Photocatalytic Performance of ZnO Nanoparticles Multilayer Films
摘要： Zinc oxide nanoparticles were synthesized by the reaction of an aqueous-alcoholic solution containing zinc nitrate hexahydrate and sodium hydroxide under ultrasonic irradiation at room temperature. The crystallinity, morphology and optical property of ZnO nanoparticles were examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible spectrophotometer. Zinc oxide nanoparticles multilayer films were prepared dipping glass slide, which had been cleaned with a piranha solution, into a ZnO solution by ultrasonic irradiation. The ZnO nanoparticles multilayer films were evaluated as a photocatalyst in the photocatalytic degradation of organic dyes, such as methylene blue, methyl orange and rhodamine B, under ultraviolet light at 254 nm.
关键词： Multilayer films,Photocatalytic activity,Zinc oxide nanoparticles,Organic dyes,UV-visible spectrophotometer
更新于2025-09-04 15:30:14
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Reversible Control of Physical Properties via an Oxygen-Vacancy-Driven Topotactic Transition in Epitaxial La <sub/>0.7</sub> Sr <sub/>0.3</sub> MnO <sub/>3?</sub><i> <sub/>δ</sub></i> Thin Films
摘要： The vacancy distribution of oxygen and its dynamics directly affect the functional response of complex oxides and their potential applications. Dynamic control of the oxygen composition may provide the possibility to deterministically tune the physical properties and establish a comprehensive understanding of the structure–property relationship in such systems. Here, an oxygen-vacancy-induced topotactic transition from perovskite to brownmillerite and vice versa in epitaxial La0.7Sr0.3MnO3?δ thin films is identified by real-time X-ray diffraction. A novel intermediate phase with a noncentered crystal structure is observed for the first time during the topotactic phase conversion which indicates a distinctive transition route. Polarized neutron reflectometry confirms an oxygen-deficient interfacial layer with drastically reduced nuclear scattering length density, further enabling a quantitative determination of the oxygen stoichiometry (La0.7Sr0.3MnO2.65) for the intermediate state. Associated physical properties of distinct topotactic phases (i.e., ferromagnetic metal and antiferromagnetic insulator) can be reversibly switched by an oxygen desorption/absorption cycling process. Importantly, a significant lowering of necessary conditions (temperatures below 100 °C and conversion time less than 30 min) for the oxygen reloading process is found. These results demonstrate the potential applications of defect engineering in the design of perovskite-based functional materials.
关键词： La0.7Sr0.3MnO3 films,polarized neutron reflectometry,brownmillerite,oxygen vacancy ordering,magnetism
更新于2025-09-04 15:30:14
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Study of the Interface of the Early Stages of Growth under Quasi-Equilibrium Conditions of ZnO on Graphene/Cu and Graphite
摘要： The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi-equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.
关键词： X-ray photoemission spectroscopy,early stages of growth,ZnO/graphene interfaces,atomic force microscopy,nanostructured ZnO thin films
更新于2025-09-04 15:30:14
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The Role of Humidity in Tuning the Texture and Electrical Properties of Cu <sub/>2</sub> O Thin Films Deposited via Aerosol‐Assisted CVD
摘要： A study on the effect of carrier gas (CG) humidity on the texture and the resulting electronic properties of Cu2O thin films deposited using aerosol-assisted chemical vapor deposition (AA-CVD) at low temperatures (<365 °C) is reported. By increasing the CG humidity, the preferred orientation of the films can be tuned from [110] to [111]. By studying the initial stages of film deposition, a different growth mode is found for dry and humid conditions, which in turn directs the final texture of the films. The analysis of the electric properties of the films by Hall effect shows that carrier concentration remains in the order of 1015 cm?3 when using both dry and humid conditions. Conversely, Cu2O samples deposited with humid CG generally present a higher mobility, up to 17 cm2 V?1 s?1. [111]-textured Cu2O films with high mobility were used to fabricate a diode by depositing a ZnO layer on top using atmospheric pressure spatial atomic layer deposition (AP-SALD). The diode shows an excellent rectifying behavior with a high asymmetry close to 104 between ?1 and +1 V.
关键词： textured thin films,copper oxides,aerosol-assisted CVD,carrier mobility,atmospheric pressure processing
更新于2025-09-04 15:30:14
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Influence of rare earth material (Sm3+) doping on the properties of electrodeposited Cu2O films for optoelectronics
摘要： Herein, we report samarium (Sm) dopant concentration effect on Cu2O films characteristics prepared by electrodeposition method. XRD patterns of the films indicated that pristine and Sm:Cu2O films have polycrystalline cubic structure with (111) preferred orientation. It was seen from the SEM photographs pinhole free dense triangle shaped grains for undoped Cu2O thin films and the grain size was decreased as concentration of samarium was increased. Raman spectroscopy showed peaks at 108, 146, 217, 413 and 637 cm?1 which conformed the Cu2O phase formation and intensity of the peaks was decreased with a increase in dopant concentration. UV–Vis spectra exhibited that the absorption value of Cu2O films is increased gradually with reduction in band gap value for the increase of samarium content. Photoluminescence (PL) spectra revealed that all films display a visible light emissions and its intensity was reduced due to increase in doping concentration. Photosensitivity observation study indicated that the photocurrent of deposited Cu2O films was increased along with the increase in dopant material concentration.
关键词： Electrodeposition,Cu2O films,Optoelectronics,Structural properties,Samarium doping,Optical properties,Photosensitivity
更新于2025-09-04 15:30:14
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Luminescent Nd <sub/>2</sub> S <sub/>3</sub> thin films: a new chemical vapour deposition route towards rare-earth sulphides
摘要： Neodymium sulphide (Nd2S3) belongs to the exciting class of rare earth sulphides (RES) and is projected to have a serious potential in a wide spectrum of application either in pure form or as dopant. We demonstrate a facile and first growth of Nd2S3 thin films via metal–organic chemical vapour deposition (MOCVD) at moderate process conditions using two new Nd precursors, namely tris(N,N’-diisopropyl-2-dimethylamido-guanidinato)Nd(III) and tris(N,N’-diisopropyl-acetamidinato)Nd(III). The promising thermal properties and suitable reactivity of both Nd precursors towards elemental sulphur enabled the formation of high purity γ-Nd2S3. While the process temperature for film growth ranged from 400 °C to 600 °C, the films were crystalline above 500 °C. We also demonstrate that the as-deposited γ-Nd2S3 are luminescent, with the optical bandgap ranging from 2.3 eV to 2.5 eV. The process circumvents post-deposition treatments such as sulfurisation to fabricate the desired Nd2S3, which paves the way for large scale synthesis and also opens up new avenues for exploring the potential of this class of materials with properties for functional applications.
关键词： MOCVD,Nd2S3,thin films,rare earth sulphides,luminescent
更新于2025-09-04 15:30:14
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Characteristics of Graphene Oxide Films Reduced by Using an Atmospheric Plasma System
摘要： The chemical oxidation method can be used to mass-produce graphene oxides (GOs) from highly oriented pyrolytic graphite. However, numerous oxygen-containing functional groups (hydroxyl, epoxy, carbonyl, etc.) exist in typical GO surfaces, resulting in serious electrical losses. Hence, GO must be processed into reduced graphene oxide (rGO) by the removal of most of the oxygen-containing functional groups. This research concentrates on the reduction efficiency of GO films that are manufactured using atmospheric-pressure and continuous plasma irradiation. Before and after sessions of plasma irradiation with various irradiation times, shelters, and working distances, the surface, physical, and electrical characteristics of homemade GO and rGO films are measured and analyzed. Experimental results showed that the sheet resistance values of rGO films with silicon or quartz shelters were markedly lower than those of GO films because the rGO films were mostly deprived of oxygen-containing functional groups. The lowest sheet resistance value and the largest carbon-to-oxygen ratio of typical rGO films were approximately 90 ?/sq and 1.522, respectively. The intensity of the C–O bond peak in typical rGO films was significantly lower than that in GO films. Moreover, the intensity of the C–C bond peak in typical rGO films was considerably higher than that in GO films.
关键词： sheet resistance,oxygen functional group,GO and rGO films,plasma irradiation,carbon-to-oxygen ratio
更新于2025-09-04 15:30:14
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Desenvolvimento de filmes poliméricos ultrafinos e reticulados para aplica??es em sensores
摘要： A new method for producing stable films used in sensors is proposed, based on the layer-by-layer deposition of poly(o-ethoxyaniline) and phenol-formaldehyde (POEA/PF) followed by a thermal treatment to promote film crosslinking. The crosslinking process was characterized by Fourier transform infrared and ultraviolet-visible spectroscopic analyses, atomic force microscopy and desorption studies. Sensor analyses were also carried out in order to evaluate cross-linked sensor signal. Results showed that PF resin served as a curing agent, forming a semi-interpenetrating polymer network therefore producing stable films. Although there was a decrease in the sensitivity of sensors with crosslinking, such films are quite stable and can be potentially used in sensors, especially where higher stability is required.
关键词： ultrathin films,conductive polymers,sensors
更新于2025-09-04 15:30:14