Sb-Se Thin Films Research Articles

Altered the structural, morphological and optical properties of SbSe thin films through swift heavy ion irradiation

Chalcogenide based phase change materials are gaining attention due to their ability to exhibit expeditious and reversible structural transition from amorphous to crystalline phase. This work included the effect of swift heavy silver (Ag9+) ion-irradiation (120 MeV), at various fluences (5E11, 1E12, 5E12 and 1E13 ions/cm2) on the structural, optical and morphological properties of pristine and annealed (250 ° C) SbSe thin films. The pristine films undergo a structural transition from amorphous to crystalline upon annealing and from crystalline to amorphous upon irradiation of annealed films. Structural transition caused by annealing and ion-irradiation resulted in a drastic change in morphology and optical properties. The annealed films exhibited less transmission than the pristine and irradiated films, which increased with increase in ion-irradiation fluences because of phase transition. After irradiation, the optical band decreased for pristine thin films, because the forbidden gap defect concentration has increased, but increased after irradiating the annealed thin films that may be due to annealing out of dense localized defect states. The significant optical contrast upon phase transition in near infrared region can be utilized for different optoelectronic applications.

Physical characterization of thermally evaporated Sn–Sb–Se thin films for solar cell applications

Physical characterization of thermally evaporated Sn–Sb–Se thin films for solar cell applications

MATHEMATICAL MODELING AND OPTIMIZATION OF THE LECTRODEPOSITION PROCESS OF ANTIMONY-SELENIUM SYSTEM

Antimony selenide (Sb2Se3), is an excellent photovoltaic absorber due to its high absorption coefficient (> 105 cm–1) at the visible region and 1.17 eV band gap. In recent years, the power conversion efficiency of Sb2Se3 thin film solar cells has gradually enhanced. Therefore, given the great interest in this material, this work is devoted to the study of a mathematical model for the optimization of the preparation of thin Sb–Se films by the electrochemical method. The study was conducted by potentiodynamic, potentiostatic and galvanostatic methods carried out under different conditions at Pt, Cu and Ni elec-trodes. The kinetics and mechanism of the electroreduction of antimony and selenite ions in the tartaric acid were studied separately for the electrochemical deposition. On the basis of cyclic polarization, X-ray phase and SEM-EDX analyses, it is found that Sb–Se thin films are deposited on Pt and Ni electrodes, but not on Cu electrode. The mathematical calculations were performed in the OptimME software package using specially developed software for this process. By studying the effects of various factors (concentration of the initial components, temperature, current density, etc.), the optimal electrolysis mode and electrolyte composition for the co-deposition process were selected. Based on these results, Student and Fisher criteria were assigned for future purposes and regression coefficients were estimated. The obtained regression equation determines the electrolyte content and the electrolysis conditions, which allows precipitating the Sb–Se alloy containing the required amount of Sb. Calculations and experimental results show that the error of the regression equation for obtaining the Sb–Se alloy is =6.4%.

Physical properties and structure characteristics of titanium-modified antimony-selenium phase change thin film

Effects of the titanium dopant on the physical properties and structure of SbSe thin films were systematically investigated by experiments and first-principles calculations. The amorphous-to-polycrystalline transformation induced by heat was examined by in situ electrical resistance measurements. With the incorporation of titanium atoms, both the crystallization temperature and electrical resistance increase, revealing the improvement of the amorphous thermal stability and programing energy consumption. X-ray diffraction, transmission electron microscopy, and density functional theory calculations illustrate that a small amount of titanium dopant can inhibit the grain growth and refine the crystal size. The shift of Raman modes associated Sb upon the crystallization was observed. X-ray reflectivity and atomic force microscopy results prove the smaller volume fluctuation and the smoother surface morphology, meaning the better interfacial property and reliability of titanium-doped SbSe materials. Phase change memory cells based on titanium-doped antimony-selenium were fabricated to evaluate the electrical performance as well. All these results indicate that the suitable incorporation of the titanium element will be an effective method to optimize the physical properties and tune the structure of the SbSe phase change material.

894 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: G5717059720/2020©BEIESP DOI: 10.35940/ijitee.G5717.059720 Journal Website: www.ijitee.org Electrical Resistivity, Thermoelectric Power and I-V Characteristics of Sb-Se Thin Films at Different Compositions.

Sb-Se thin films of varying composition have been deposited on glass substrates at room temperature. These films were annealed at temperature interval of 50 0K. The electrical resistivity (ρ) and thermoelectric power (α) of same films were measured. The resistance of semiconducting films decreases rapidly on heating showing negative temperature coefficient of resistance (T.C.R.). The composition dependent resistivity shows exponential change, sharp fall of resistivity may be attributed due to increase of metallic ‘Sb’ in Sb-Se thin films. The composition dependent activation energy of Sb-Se thin films has been calculated. The activation energy (ΔE) of semiconducting films was found to increase with selenium concentration. For different compositions thermoelectric power (α) increases upto 70 at. wt.% of Se concentration and then slowly decreases. The I-V characteristics of Sb-Se thin films were measured using copper (Cu) contacts. The films show ohmic conduction for different applied voltages as well as various concentrations of Selenium (Se) in Sb-Se thin films.

Amorphous Ga–Sb–Se thin films fabricated by co-sputtering

Ternary chalcogenides of a Ga–Sb–Se system are prospective materials for potential applications in the field of infrared optics. This Letter deals with the optical properties and photosensitivity of Ga–Sb–Se thin films deposited by co-sputtering, enabling us to fabricate amorphous thin films outside the glass-forming region. The optical bandgap range of 1.92–1.35 eV with corresponding refractive indices at 1.55 µm ranging from 2.47 to 3.33 can be reliably covered using G a 2 S e 3 and S b 2 S e 3 targets. Furthermore, the prolonged irradiation by the near-bandgap light under the pure argon atmosphere leads to the irreversible photo-bleaching effect in fabricated films. The magnitude of this effect decreases monotonically with an increasing antimony content.

Electrodeposition of the Sb2Se3 thin films on various substrates from the tartaric electrolyte

The present contribution is devoted to the electrochemical deposition of Sb2Se3 thin films from tartrate electrolyte. The study was conducted by potentiodynamic, potentiostatic and galvanostatic methods carried out under different conditions at Pt, Cu and Ni electrodes. The kinetics and mechanism of the electroreduction of antimony and selenite ions in the tartaric acid were studied separately for the electrochemical deposition. Comparison of the obtained polarization curves showed that co-deposition occurs between electroreduction potentials of antimony and selenium, indicating depolarization electrode effect for antimony ions. The influence of electrolyte compo­sition, pH, current density, temperature, etc. has been studied. On the basis of cyclic polarization, X-ray phase and SEM-EDX analyses, it is found that Sb-Se thin films are deposited on Pt and Ni electrodes, but not on Cu electrode. Black, uniform, crystalline and shiny films of the stoichiometric composition of Sb2Se3 compound are deposited on Pt and Ni electrodes within the 338-348 K temperature interval, pH 1.85, current density of 2.5-3.0 A/dm2, and annealing temperature of 703 K. Experiments were carried out using the optimal electrolyte composition containing 0.05 M SbOCl + 0.05 M H2SeO3 + 0.007 M C4H6O6.

Amorphous Ge‐Sb‐Se thin films fabricated by co‐sputtering: Properties and photosensitivity

AbstractAmorphous Ge–Sb–Se thin films were fabricated by a rf‐magnetron co‐sputtering technique employing the following cathodes: GeSe2, Sb2Se3, and Ge28Sb12Se60. The influence of the composition, determined by energy‐dispersive X‐ray spectroscopy, on the optical properties was studied. Optical properties were analyzed based on variable angle spectroscopic ellipsometry and UV‐Vis‐NIR spectrophotometry. The results show that the optical bandgap range 1.35‐2.08 eV with corresponding refractive index ranging from 3.33 to 2.36 can be reliably covered. Furthermore, morphological and topographical properties of selenide‐sputtered films studied by scanning electron microscopy and atomic force microscopy showed a good quality of fabricated films. In addition, structure of the films was controlled using Raman scattering spectroscopy. Finally, irreversible photoinduced changes by means of change in optical bandgap energy and refractive index of co‐sputtered films were studied revealing the photobleaching effect in Ge‐rich films when irradiated by near‐bandgap light under Ar atmosphere. The photobleaching effect tends to decrease with increasing antimony content.

Optical band gap tuning of Sb-Se thin films for xerographic based applications

In the present paper we have studied the effect of Sb addition on the optical band gap tuning of thermally evaporated SbxSe100-x (x = 0, 5, 20, 50 and 60) thin films. The structural investigations revealed that all thin films were amorphous in nature. Transmission spectrum was taken in the range 400–2500 nm shows that all films are highly transparent in the near infrared region. The fundamental absorption edge shifts towards longer wavelength with Sb incorporation. The optical band gap decreases with addition of antimony in a-Se thin films. A good correlation has been drawn between experimentally estimated and theoretically calculated optical band gap. The decrease in optical band gap of thin films has been explained using chemical bond approach and density of states model. Decrease in optical band gap with Sb addition increases the concentration of electron deep traps which increases the X-ray sensitivity of Sb-Se thin films. Thus by tuning the optical band gap of Sb-Se alloy, it could be utilized for xerographic based applications.

Optical and structural properties of Ge–Sb–Se thin films fabricated by sputtering and thermal evaporation

We deposited Ge28Sb12Se60 chalcogenide films using either thermal evaporation or radio-frequency magnetron sputtering techniques, and then measured their structural and optical properties using various diagnosis tools. The refractive indices of the films were obtained from the transmission spectra based on Swanepoel method, and the optical band gaps were derived from optical absorption spectra using the Tauc plot. Raman and X-ray photoelectron spectra (XPS) were measured and decomposed into several peaks that correspond to the different structural units, and then the evolution of the relative concentrations of the structural units was investigated in order to build up the correlation between the structure and optical properties of the films. It was found that, the films generally possess a large number of Ge2Se6/2, Sb2Se4/2 units and Se–Se bonds, and therefore are relatively higher defective compared with their bulk counterpart. This together with the modification of the chemical compositions results in a higher refractive index as well as a smaller optical band gap in the films. Thermal annealing of the deposited films could convert the optical and structure properties of the films close to those of bulk glass.

Selective Wet-Etching of Amorphous/Crystallized Sb-Se Thin Films

Selective Wet-Etching of Amorphous/Crystallized Sb-Se Thin Films The paper is focused on the development of an in situ real-time method for studying the process of wet chemical etching of thin films. The results of studies demonstrate the adequate etching selectivity for all thin film SbxSe100-x (x = 0, 20, 40, 50, 100) compositions under consideration. Different etching rates for the as-deposited and laser exposed areas were found to depend on the sample composition. The highest achieved etching rate was 1.8 nm/s for Sb40Se60 samples.

Surface Modification of SB-SE Thin Films by Laser Irradiation and Etching

Surface Modification of SB-SE Thin Films by Laser Irradiation and Etching The surfaces of Sb20Se80 and Sb40Se60 thin films were modified by exposure to laser light. To study the topology of these surfaces the scanning force microscopy was used. As a result, the surface of as-deposited/amorphous SbxSe100-x films appear to be flat, while the treated films exhibit three types of surface structure on the sub-micrometer scale. Changes in the surface characteristics as well as potential applications of selective etching of Sb-Se thin films are discussed.

Calorimetric study of amorphous Sb–Se thin films

The crystallization of amorphous Sb x Se 100− x (40≤ x≤70 at.%) alloy thin films prepared by vacuum deposition was studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The crystalline phases were identified as Sb 2Se 3 and Sb. The compositional dependence of the glass transition and crystallization temperatures as well as the heat of crystallization were determined all of them being with maximal values at composition close to the eutectics of the Sb–Se system. These thermodynamic quantities decrease with further increasing of the antimony concentration in thin films. The crystallization kinetics was measured using non-isothermal treatment mainly. The effective activation energies of crystallization were estimated to be in the 2.48–2.66 eV range and the frequency factors were between 10 26–10 28 s −1.

Effect of the substrate temperature on the properties of spray deposited Sb–Se thin films from non-aqueous medium

Semiconducting Sb–Se thin films are prepared on glass substrates from a non-aqueous medium using a spray pyrolysis technique. The films are deposited at a fixed solution concentration of 0.1 M and at various substrate temperatures. The film thickness is of the order of 0.5 μm and is found to be relatively higher for the film deposited at 175°C substrate temperature. X-ray diffraction studies reveal that the as deposited films are amorphous in nature, while after annealing in the N 2 atmosphere at 325°C for 2 h, the films deposited at 200°C turn into polycrystalline ones. The analysis of the absorption coefficient data reveals that as the substrate temperature increases, the optical bandgap value of the material increases. It has also been found, for the film deposited at 200°C and annealed in N 2 atmosphere, that the polycrystalline material follows the direct optical transition with energy gap Eg opt equal to 2.14 eV. The electrical resistivity at room temperature (300 K) is of the order of 10 6–10 7 Ω cm, which changes slightly after annealing.

Composition dependence of electrical properties of simultaneously evaporated Sb-Se thin films

Amorphous thin films of Sb-Se are prepared using the three-temperature method. The films are prepared with atomic compositions from 5–90 at.% Sb. The electrical resistivity, Hall voltage and thermoelectric power of annealed samples have been measured in the temperature range 25 to 250°C. On heat treatment the sharp fall of resistance of the annealed films is attributed to radical structural transformation from amorphous to crystalline. Electrical resistivity, Hall constant and thermoelectric power are found to vary with thickness and composition of the film.

Negative resist behavior of obliquely deposited Ge–Sb–Se thin films

The photon and electron-beam induced changes in the selective solubility of Ge–Se–Sb films have been investigated to show that these films can be used as a negative resist. The formation of Sb2Se3 on the top of the film surface after exposure, as confirmed by x-ray diffraction and x-ray photoelectron spectroscopy studies, gives rise to a negative tone behavior. The addition of 10 at. % of Sb in the GeSe3 films saturates the change in the chemical solubility after photo- and electron-beam exposures. The chemical solubility difference can be increased by increasing the angle of deposition and is maximum at 80°. Contrast (γ) and sensitivity (s) values of 2.85 and ∼1020 photons/cm2, respectively, for photons, and 4.2 and 6×10−5 C/cm2 for electrons have been obtained.