Pulsed Photon Treatment Research Articles

Hydrogen permeability of 48Cu52Pd cold-rolled alloy foil and different methods of its surface pretreatment

The process of atomic hydrogen penetration into the metal phase is complicated by the phase-boundary transition from the liquid and/or gas phase. That is why the cleanliness of metal and alloy surfaces is of particular importance. The purpose of this work was to determine the effect of surface pretreatment using photon pulses, ultrasound, and potential cycling on the parameters of hydrogen permeability for 48Cu52Pd metal cold-rolled membranes. The study was focused on a foil of copper-palladium homogeneous alloy with 48 at. % Cu and 52 at. % Pd composition. The studied samples were obtained by cold rolling and their thickness were 10 and 16 μm. Surface pretreatment included rinsing in acetone, using ultrasound, pulsed photon treatment, and quadruple potential cycling over a wide range of potentials. Electrochemical studies included cyclic voltammetry and cathode-anodic chronoamperometry in a deaerated 0.1 M H2SO4 solution. Hydrogen permeability was calculated using mathematical models for samples of finite and semi-infinite thickness. It was found that the surface treatment of a 48Cu52Pd foil with photon pulses leads to both an increase in the ionisation rate of atomic hydrogen and an increase in the roughness of the foil surface. The diffusion coefficient of atomic hydrogen does not depend on the method of surface pretreatment with ultrasound and photon pulses. The extraction rate constant for the extraction of the atomic hydrogen after photon treatment increases, which facilitates the processes of both H introduction and ionisation due to the release of active centres of the surface. Electrochemical cleaning of the surface during the quadruple potential cycling contributes to the growth of the extraction rate constant for the extraction of atomic hydrogen

Activation of film growth on indium phosphide by pulsed photon treatment

Photon activation of various physicochemical processes by the radiation of powerful pulsed xenon lamps (radiation range of 0.2-1.2 µm) is one of the promising areas of material science. The aim of this study was to determine the effect of preoxidative pulsed photon treatment on the process of thermal oxidation of indium phosphide with a nanosized layer of V2O5 on the surface, as well as its effect on the composition and morphology of the formed films. We determined the optimal mode of pre-oxidative pulsed photon treatment of magnetron-formed V2O5/InP heterostructures with a radiation density of 15 J/cm2. By laser and spectral ellipsometry methods, photon activation of V2O5/InP before thermal oxidation was found to increase the thickness of the formed films practically twofold. X-ray diffraction analysis confirms the intensification of the phosphate formation process. The morphological characteristics of the films were determined by atomic force microscopy.Pre-oxidative pulsed photon treatment with an optimal radiation density of 15 J/cm2 activates the thermal oxidation of V2O5/InP heterostructures. It is associated with the formation of new active centres and accelerated rearrangement of chemical bonds in the intermediate complexes of the V2O5 catalyst with semiconductor components

Pulsed photon treatment effect on the optical bandgap of LiNbO3 films grown by radio-frequency magnetron sputtering method

Pulsed photon treatment effect on the optical bandgap of LiNbO3 films grown by radio-frequency magnetron sputtering method

Synthesis and properties of NiSi2-LiNbO3 heterostructures fabricated by radio-frequency magnetron sputtering

Thin LiNbO3 films were synthesized by radio-frequency the magnetron sputtering method on nickel silicide (NiSi2) substrates in a pure Ar atmosphere and an Ar+O2 gas mixture. The as-grown LN-NiSi2 heterostructures fabricated in an Ar environment exhibited high-quality rectifying current-voltage (I-V) characteristics due to the presence of an oxide charge, making the band diagram nonsymmetrical. The charge transport is determined by space-charge-limited currents via electronic traps distributed in the bandgap of LiNbO3 with a concentration of Nt=2.0•1015 cm-3. By contrast, I-V characteristics of LN-NiSi2 heterostructures fabricated in an Ar+O2 gas mixture were symmetrical due to decreasing in the oxide charge amount. The trap concentration rises to Nt=3.0•1018 cm-3 when the oxygen content in a reactive chamber increases to 60%. As-grown LiNbO3 films manifested good isolating properties with the resistivity of 8•109 Ohm•cm. The pulsed photon treatment increases the resistivity of LN films by six orders of magnitude, turning their I-V characteristics into Ohmic-like which makes this post-growth technique not suitable for the studied heterostructures.

Effect of Pulsed Photon Treatment on Electrophysical and Thermophysical Properties of n-Type Solid Solution Based on Bi2Te3–Bi2Se3: I. Electrophysical Properties

The effect of the pulsed photon treatment exerted on the electrical conductivity, the thermal EMF, and the power factor of n-type solid solution Bi2Te3–Bi2Se3 has been studied. The samples have been obtained by means of powder metallurgy in two stages consisting in the synthesis and hot pressing in an argon atmosphere. It has been found that the pulsed photon treatment in an argon atmosphere of samples synthesized by means of powder metallurgy leads to the surface layer recrystallization and to the changes in the phase composition owing to selenium sublimation. As a result of this, the concentration of free charge carriers in the material decreases, the thermal EMF exhibits an increase, and the electrical conductivity decreases. Depending on the pulse intensity, the mobility of free charge carriers can either decrease or increase. This makes it possible to choose a mode of pulsed photonic processing wherein the relative increase in the thermal EMF exceeds the decrease in the electrical conductivity of the material, as a result of which the power factor of the material exhibits a 2.6% increase.

Effect of Pulsed Photon Treatment on Electrophysical and Thermophysical Properties of n-Type Solid Solution Based on Bi2Te3–Bi2Se3: II. Thermal Conductivity and Thermoelectric Figure of Merit

The effect of pulsed photon treatment on the thermal conductivity and thermoelectric figure of merit of n-type Bi2Te3–Bi2Se3 solid solution has been studied. The samples have been obtained by powder metallurgy by synthesis and hot pressing in an argon atmosphere. It has been found that pulsed photon treatment of samples in an argon atmosphere leads to a decrease in the thermal conductivity of the sample. In this case, the electronic component of the thermal conductivity exhibits a decrease regardless of the treatment mode owing to a decrease in the electronic component of heat capacity, whereas the phonon component decreases only in the range of relatively high irradiation doses. An optimal mode of pulsed photon treatment has been determined, wherein the decrease in the thermal conductivity of the material occurs simultaneously with an increase in the power factor, while the thermoelectric figure of merit exhibits an almost 10% increase.

Effect of Pulsed Photon Treatment on the Mechanical Properties of Semiconductor Thermoelectric Legs, Based on Bi2Te3–Bi2Se3 Solid Solutions, and the Adhesion of Switching Layers

We carry out comparative studies of the phase composition, morphology, and hardness of semiconductor legs based on the n-type solid solution Bi2Te3−Bi2Se3, obtained by hot pressing, after surface modification (mechanical processing and pulsed photon treatment (PPT) with incoherent light). Using shear tests, we determine the adhesion of switching and barrier Mo–Ni layers on the modified surfaces of semiconductor legs. Pulsed photon treatment stimulates local recrystallization of the imperfect layer near the surface of samples of the Bi2Te3−Bi2Se3 solid solution to a depth of 100−200 nm, which increases the hardness of the surface layers. It is shown that the mechanical polishing and subsequent pulsed photon treatment of thermoelectric legs increases the adhesion of the switching and barrier Mo–Ni layers by 3–4 times, which can contribute to the efficient and stable operation of a thermoelectric generator battery.

Влияние фотонной обработки на электро- и теплофизические свойства твердого раствора n-типа на основе Bi2Te3-Bi2Se3. I. Электрофизические свойства

Влияние фотонной обработки на электро- и теплофизические свойства твердого раствора n-типа на основе Bi2Te3-Bi2Se3. I. Электрофизические свойства

Влияние фотонной обработки на электро- и теплофизические свойства твердого раствора n-типа на основе Bi2Te3-Bi2Se3. II. Теплопроводность и термоэлектрическая добротность

Влияние фотонной обработки на электро- и теплофизические свойства твердого раствора n-типа на основе Bi2Te3-Bi2Se3. II. Теплопроводность и термоэлектрическая добротность

ПОВЫШЕНИЕ АДГЕЗИОННЫХ СВОЙСТВ КОММУТАЦИОННЫХ СЛОЁВ НА ПОЛУПРОВОДНИКОВЫХ ВЕТВЯХ р-ТИПА ТЕРМОЭЛЕКТРИЧЕСКИХ ГЕНЕРАТОРНЫХ БАТАРЕЙ

Проведены сравнительные исследования фазового состава, морфологии, твердости и адгезии поверхности полупроводниковых термоэлектрических ветвей на основе твердого раствора Bi2Te3-Sb2Te3 р-типа проводимости, полученных методом горячего прессования, после модификации поверхности различными методами (механическая обработка (МП), импульсная фотонная обработка (ИФО), электрохимическая полировка (ЭХП)). Установлено, что МП упрочняет приповерхностный слой, повышает в 2 раза адгезию коммутационных барьерных слоев Mo–Ni. Последующие ЭХП повышает адгезию слоев Mo–Ni в 1.3 раза, а ИФО в 1.4 раза в сравнении с ветвями после МП.
 
 Работа выполнена с использованием научного оборудования Центра коллективного пользования им. проф. Ю. М. Борисова ВГТУ, Центрально-Черноземного коллективного центра анализа структуры, элементного и химического состава материалов ВГТУ и при финансовой поддержке Министерства образования и науки Российской Федерации в рамках постановления Правительства Российской Федерации от 9 апреля 2010г. №218 (Договор № 03.G25.31.0246).

GROWTH PROCESSES OF SUBGRAIN AND MORPHOLOGY EVOLUTION IN THE SYNTHESIS OF Β-SiC FILMS AT (111) Si IN THE ATMOSPHERE OF METHANE

By the methods of transmission electron microscopy, high energy electron diffraction, atomic force microscopy, and Auger electron spectroscopy, the article studies the phase composition, orientation, substructure, and morphology of the films formed during pulsed photon treatment (PPT) by radiation of xenon lamps of silicon (111) Si substrates in an atmosphere of methane. We have established that in the range of the energy density of radiation (Ep) supplied to the substrate with a thickness of 0.45 μm for 3 s from 269 to 284 J cm-2 the oriented nanocrystalline films are formed on both surfaces of the substrates both from the irradiated and non-irradiated side β-SiC thickness of about 150 nm. In this case, the synthesis of films on the irradiated side is carried out with the possible participation of photon activation of processes and on the reverse side – only by thermal activation (short-term heat treatment (SHT). With an increase in the energy density of radiation in β-SiC films, the average subgrain size on the irradiated side is shown to increase from 4.2 nm (Ep = 269 J ·cm-2) to 7.9 nm (Ep = 284 J ·cm-2) and on the non-irradiated side 3.9 to 7.0 nm respectively. The surface roughness of the β-SiC surface proceeds consequentially on the irradiated side from 19 nm (Ep = 269 J ·cm-2) to 60 nm (Ep = 284 J ·cm-2) and on the non-irradiated side from 11 nm to 56 nm respectively. Based on the temperature dependences of the average grain size and roughness, we have estimated the apparent activation energies of the processes. The activation energy of subgrain β-SiC growth is practically independent of the activation method and is 1.3 eV. The activation energy for the evolution of roughness is 2.5 eV at a PPT and 3.5 eV at a SHT.

Activation energy of subgrain growth process and morphology evolution in β-SiC/Si(111) heterostructures synthesized by pulse photon treatment method in a methane atmosphere

Single-phase β-SiC films were grown by the pulsed photon treatment (PPT) of (111)Si wafers with the use of xenon lamp radiation in a methane atmosphere. Study of phase composition, structure and morphology revealed that β-SiC oriented nanocrystalline films are formed onto both non-irradiated and irradiated surfaces under the radiation energy range from 269 to 284 J cm−2 supplied for 3 s. The non-irradiated side was undergone the rapid thermal annealing (RTA). It is demonstrated that the average subgrain size increases from 4.2 nm (Ep = 269 J cm−2) to 7.9 nm (Ep = 284 J cm−2) and from 3.9 to 7.0 nm for the irradiated and non-irradiated sides respectively when radiation energy density rises. The surface roughness of β-SiC films increases gradually from 19 to 60 nm and from 11 to 56 nm on irradiated and non-irradiated sides respectively in the same radiation energy density range. The β-SiC subgrain growth activation energy is 1.3 eV and it does not depend on the activation method. The surface roughness evolves with the activation energy of 2.5 eV and 3.5 eV for PPT and RTA respectively.

Effect of different types of annealing on the thermal oxidation of V x O y /InP structures formed by the deposition of vanadium(V) oxide gel on the phase composition and morphology of films

The effect of different types of annealing (thermal or pulsed photon) of V x O y /InP structures synthesized using vanadium pentoxide gel on the process of their thermal oxidation, and the phase composition and morphology of the films are studied by the methods of X-ray phase analysis (XRD), Auger electron spectroscopy (AES), and scanning tunneling microscopy (STM). Thermal annealing makes it possible to synthesize films with a smoother surface relief in the absence of film-substrate interaction before thermal oxidation. Pulsed photon treatment compared with thermal annealing leads to more effective and rapid crystallization of the amorphous phase of the V2O5 gel and faster growth of oxide films during the thermal oxidation of V x O y /InP structures. As a result, pulsed photon treatment leads to the formation of InVO4 as a product of the interaction between the semiconductor substrate and the chemostimulator, which is an attribute of the “hard” methods of chemostimulator deposition, i.e., magnetron sputtering and electric explosion of the conductor.

Synthesis of thin p-type rutile films

The structure and electrical and optical properties of heterostructures formed on the surface of single-crystal silicon wafers as a result of the heat treatment and pulsed photon treatment of Ti films in oxygen, air, and nitrogen are investigated. It is shown that a TiO2/Ti5Si3/p-Si heterostructure is formed upon heat treatment in air, whereas a TiO2/TiSi2/p-Si heterostructure is formed upon photon treatment. It is established that rutile films with pronounced n-type conductivity are formed as a result of the heat treatment of Ni-doped Ti films in oxygen. Rutile films with p-type conductivity are formed upon the thermal annealing of Ti films in air with subsequent photon treatment in nitrogen.

Synthesis of nanostructured SiC films during pulsed photon treatment of Si in a carbon-containing atmosphere

The phase composition, orientation, substructure, and morphology of the films formed during pulsed photon treatment of a single-crystal Si surface by xenon lamp irradiation (λ = 0.2–1.2 µm) and polycrystalline Si films on SiO2-Si in a gaseous atmosphere (C3H8)0.2(C4H10)0.8 are investigated using the methods of transmission electron microscopy, high-energy electron diffraction, atomic force microscopy, and IR-spectroscopy. The irradiation time (the duration of the pulse packet) varied from 1.5 to 2.0 s, which corresponded to variations in the incident’s irradiation energy (Ep) from 215 to 285 J · cm−2. The threshold value of Ep was determined. The films of SiC and Si are characterized by a nanocrystalline substructure and biaxial texture, corresponding to different deviations of grains from parallel epitaxial orientation. The portion of epitaxially oriented grains rising to the film surface is increasing with an increase in Ep and the film thickness. Under the conditions necessary for the formation of a eutectic melt in the near-surface zone, the crystallization yielding the formation of a uniaxial texture takes place. During the synthesis on doped poly-Si films the forming SiC film inherits the texture of the layered substructure of the initial Si’s film blocks.

Control of the properties of thin-film systems with the use of pulsed photon treatment

We have developed a radically new technological process of making very large‐scale integrated circuits, which has no analogs and is based on the use of fast heat treatments for forming gettering layers, silicon oxidation, annealing of ion‐doped layers, fusion of phosphoro‐ and borophosphorosilicate glasses, forming silicides, and increasing the thermostability of aluminum metallization.

ChemInform Abstract: Use of Pulsed Photon Treatment for the Synthesis of CuInSe2 Films.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Pulsed photon treatment of CuInSe2 films

CuInSe2 with a tetragonal chalcopyrite structure was shown to form upon pulsed photon treatment (xenon lamps) of amorphous nearly stoichiometric films prepared by vacuum coevaporation from elemental sources. The film structure was studied by x-ray and electron diffraction techniques.

Possible method of reducing annealing temperatures of radiation defects in ion-implanted silicon carbide

It is shown that the temperatures of post-implantation annealing of radiation defects in silicon carbide may be reduced by pulsed photon treatment. With a correct choice of spectral composition and radiation energy, pulsed photon treatment is effective for annealing radiation defects through the selective absorption of photons at the corresponding levels. It is suggested that the annealing mechanism is ionizational (annealing under these experimental conditions cannot be explained by a thermal mechanism alone).

Electron Stimulated Defect Reactions in Silicon under Pulsed Photon Treatment

Electron Stimulated Defect Reactions in Silicon under Pulsed Photon Treatment