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Structural and thermoelectric properties of Se doped In <sub/>2</sub> Te <sub/>3</sub> thin films
摘要： The Se-Te based chalcogenides exhibit novel property of Phase Change Memory (PCM) which has potential applications in electrical non-volatile memories. These materials are also suitable in thermal to electrical energy conversions and, hence, of potential interest in energy sustainability as thermoelectric devices. In this study, the Se doped In2Te3 thin films were prepared by thermal evaporation and were annealed at 250 ?C and 300 ?C in Argon gas. The X-ray diffraction spectra show that thermal annealing leads to the phase transitions in Se doped In2Te3 into binary phases of In2Se3 and In2Te3. The surface morphology of the films exhibits the grains of spherical nature. Annealing also decreases the energy band gap due to the presence of two phases. From the four probe and photoconductivity measurements, a large contrast in electrical resistance between the amorphous and crystalline states is found with a variation of a few orders of magnitude. The electrical transport properties such as the electrical resistivity, Seebeck coefficient and the power factor were measured in the temperature range from 300 K to 430 K. All the deposited and annealed thin films exhibit n-type conductivity with the Seebeck coefficient ranging from -338 μVK-1 to -510 μVK-1. An increase in thermoelectric power of 25% is observed in the 300 ?C annealed films in comparison to the as-deposited films. Moreover, the lower Se doped In2(Te0.96Se0.04)3 compound exhibits a better thermoelectric performance compared to the In2(Te0.90Se0.1)3 composition. This study shows the multifunctional nature of Se doped In2Te3 both for PCM and thermoelectric applications.
关键词： power factor,Seebeck coefficient,Phase Change Memory,X-ray diffraction,thermal evaporation,Se-Te based chalcogenides,electrical resistance,thermoelectric devices
更新于2025-09-10 09:29:36
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Change in the morphology of SnO<sub>2</sub> crystals synthesized by thermal evaporation of SnO<sub>2</sub> powder mixed with graphite in ambient air
摘要： The morphology of tin oxide (SnO2) crystals, which were formed by thermal evaporation of SnO2/graphite powder mixture, was changed with the ratio of graphite to SnO2 powder in the source material. The synthesis process was performed in air at atmospheric pressure and no catalysts and substrates were used, which makes the process very simple and low cost. At the low ratios of graphite to SnO2 powder in the source material, the SnO2 crystals had a spherical shape with nanometer dimensions. With increasing the ratio of graphite to SnO2 powder, the morphology of SnO2 crystals changed from particle to belt. The belt-shaped SnO2 crystals had the widths in the range of 1.2–3.1 μm and the lengths of several tens of micrometers. X-ray diffraction analysis showed that all the SnO2 crystals had a rutile tetragonal crystal structure. Visible emission band with the wavelength in the range of 400–600 nm was observed in the cathodoluminescence spectra of the SnO2 crystals.
关键词： Graphite,Mixing ratio,Air,Tin oxide,Thermal evaporation,Morphology variation
更新于2025-09-10 09:29:36
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Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes
摘要： A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex donor-acceptor emitters is presented. With a step-by-step procedure, readers will be able to repeat and produce OLED devices based on simple organic emitters. A patterning procedure allowing the creation of personalized indium tin oxide (ITO) shape is shown. This is followed by the evaporation of all layers, encapsulation and characterization of each individual device. The end goal is to present a procedure that will give the opportunity to repeat the information presented in cited publication but also using different compounds and structures in order to prepare efficient OLEDs.
关键词： ambipolar,Donor-Acceptor,Thermally Activated Delayed Fluorescence,exciplex,Organic Electronics,patterning,thermal evaporation,Issue 141,OLED,Engineering
更新于2025-09-09 09:28:46
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Optical characterisation of amorphous Se–Te–Sn thin films
摘要： Optical characterization of Sn doped Se–Te thin films has been carried out. The characterization has been carried out using transmission spectra in range 500–2500 nm. Bulk samples were prepared using melt quenching technique and thin films were deposited using thermal evaporation. XRD analysis was used to confirm the amorphous nature of prepared samples. Optical constants such as refractive index and extinction coefficient have been determined using Swanepoel’s method. Variation of refractive index with wavelength has been analysed using single effective oscillator model. Optical band gap of the deposited films was calculated using Tauc plots. The observed properties have been explained using the chemical bond approach.
关键词： Tauc plots,Swanepoel’s method,melt quenching technique,thermal evaporation,Se–Te–Sn thin films,Optical characterization
更新于2025-09-09 09:28:46
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Al2O3 thin films deposition by reactive evaporation of Al in anodic arc with high levels of metal ionization
摘要： The results of studying the parameters of the plasma generated in an arc with a self-heating hollow cathode and a vaporizable anode placed in a magnetic field of two oppositely connected solenoids are presented. Compression of the discharge column in an inhomogeneous magnetic field provides an increase in power density on the surface of the crucible anode to ~ 1 kW/cm2 and an increase in the degree of ionization of the metal vapor to 50-80%. Using the method of reactive evaporation of aluminum in the Ar/О2 gas mixture we obtained Al2O3 coatings at the rate of 4-8 μm/h under an ion current density of 6-11 mA/cm2, a bias voltage of 50-200 V, and a temperature of 620 oС. It is shown that, with an increase in the ion current density and ion energy, the fraction of the α-phase in the Al2O3 coating increases to 100%. The single-phase α-Al2O3 coatings are characterized by the predominant orientation of crystallites (300).
关键词： reactive thermal evaporation,Al2O3 coating,α-Al2O3,ion assistance
更新于2025-09-04 15:30:14