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Effect of Na doping on structural and optical properties in Cu2ZnSnS4 thin films synthesized by thermal evaporation method
摘要： Quaternary chalcogenide Cu2ZnSnS4 (CZTS) compound, a potential material for application as absorber layer in thin film solar cells, is synthesized by direct melting of the constituent elements taken in stoichiometry compositions. Alkali element Na was incorporated into CZTS thin films synthesized by thermal evaporation method, in order to further improve the structural and optical properties. X-Ray diffraction (XRD), Raman spectroscopy, Energy dispersive spectrometry and optical spectrophotometry were used to characterise the phase purity and optical properties. It showed that the diffusion of Na ions is uniform in the films after annealing. XRD analysis showed that CZTS films possess polycrystalline structure with [221] preferred orientation. Na ions incorporation in CZTS thin films could improve the cristallinity, the graine size and the absorption coefficient. For CZTS: Na 5%, optical results revealed higher absorption coefficient (>105 cm-1) and direct optical band gap of 1.56 eV with p-type conductivity.
关键词： Semiconductors,Sodium doping,Structural properties,Optical properties,Copper zinc tin sulfide,Thin films,Thermal evaporation
更新于2025-09-23 15:23:52
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Investigation of gamma irradiation effects on the properties of CdS/p-Si heterostructure
摘要： Cadmium sulfide (CdS) thin films were deposited on p-type Si substrate by thermal evaporation to fabricate the CdS/p-Si heterojunction. Gamma irradiation has been used to modify the microstructural, optical and electrical characteristics of CdS/p-Si heterojunction of various doses in the range (0–80 kGy). X-ray diffraction measurements of the gamma irradiated show the reduction in crystallinity of the CdS thin films. While scanning electron microscope images depicted the average CdS particle size was found to be increased with increasing the gamma irradiation dose. Photoluminescence results revealed that at the specific dose of gamma irradiation was found to create the yellow emission in interstitial sites to the valence band. The I–V characteristics showed the current transport properties effected by the different gamma doses. The values of barrier height, saturation current and ideality factor for the CdS/p-Si heterostructure varied due to the causes like inhomogeneities in the interfacial, defect density, charge distribution on interfacial and interfacial layer thickness after gamma irradiation. The gamma irradiation induced effects and the possible mechanism in CdS/p-Si heterojunction is discussed.
关键词： Heterostructure,Diffuse reflectance,Photoluminescence,Gamma irradiation,Thermal evaporation
更新于2025-09-23 15:23:52
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Effect of thickness and post deposition annealing temperature on the structural and optical properties of thermally evaporated molybdenum oxide films
摘要： In this paper, the influence of thickness and post deposition annealing temperature on thermally evaporated molybdenum oxide films has been studied. The X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) are used for crystal structural and surface morphological characterization of the films, respectively. The XRD analysis showed that the presence of α-MoO3 and MoO2 crystalline phase of the films annealed at elevated temperature ~ 250 °C after deposition. The optical constants are determined from UV–Vis transmission spectra. The optical band gap and Urbach energy is found to be temperature dependent. The refractive index of the films is estimated by the optical method as well as cross-sectional SEM image analysis. It is found that the refractive index of the films increases from ~ 1.70 to 2.03 with the decrease in film thickness from ~ 2.9 to 1.7 μm. It is also observed that the refractive index decreased from ~ 2.03 to 1.61 with the increase in post deposition annealing temperature from room temperature (RT) to ~ 250 °C. Moreover, extinction coefficient, optical conductivity, porosity, and film density are investigated as a function of source-substrate distance and post deposition annealing temperature. The Photoluminescence (PL) properties of the films are also investigated by recording spectra under the excitation wavelength at 250 nm.
关键词： Optical constants,Molybdenum oxide,X-ray diffraction,Thermal evaporation,Scanning electron microscope
更新于2025-09-23 15:22:29
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Preferred orientation of 2,7-dioctyl[1]benzothieno[3,2- <i>b</i> ][1]benzothiophene molecules on inorganic single-crystal substrates with various orientations
摘要： The organic molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) was deposited on quartz glass, e11 (cid:2)20T A-, (0001) C-, and e1 (cid:2)102T R-single-crystal Al2O3 (sapphire), and (100)-, and (111)-single-crystal MgO substrates by vacuum thermal evaporation, and structural characterizations were carried out by X-ray di?raction analysis and atomic force microscopy (AFM) observation. The (001) out-of-plane orientation with a similar in-plane orientation was obtained irrespective of the substrate material and orientation, and its formation was governed by π–π-stacking-induced molecular ordering. The degree of orientation was re?ected by the grain structure related to the substrate material. The growth model of the oriented C8-BTBT layer was speculated on the basis of experimental results.
关键词： π–π-stacking,vacuum thermal evaporation,X-ray diffraction,C8-BTBT,atomic force microscopy
更新于2025-09-23 15:21:21
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Improved Performance of Thermally Evaporated Sb2Se3 Thin-Film Solar Cells via Substrate-Cooling-Speed Control and Hydrogen-Sulfide Treatment
摘要： Antimony selenide is a promising abundant absorber material for solar cells. However, current Sb2Se3 photovoltaic devices, which are fabricated via thermal evaporation, tend to have stoichiometric problems and show suboptimal performance. In this paper, we use a modified thermal evaporator to fabricate high-quality Sb2Se3 films. By dedicatedly cooling the substrate, we can improve both the Sb2Se3 morphology and the Sb2Se3/CdS heterojunction interface substantially. We find a suitable annealing atmosphere, H2S, which can largely compensate for possible deficiencies of Se and remove the antimony-oxide layer on the film surface. Thanks to cooling control and H2S treatment, we obtain a significantly improved efficiency (6.24%) for the Sb2Se3 solar cells. Our results indicate that this thermal evaporation technique is a promising approach to improve the large-scale fabrication of antimony chalcogenide solar cells.
关键词： Thermal evaporation,Sb2Se3,Hydrogen-sulfide,Large-scale,Post-annealing process
更新于2025-09-23 15:21:01
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Commitment Between Roughness and Crystallite Size in the Vanadium Oxide Thin Film opto-electrochemical Properties
摘要： The V2O5 thin films has been widely studied because it has application as ionic host in electrochromic and lithium-ion batteries, two technologies that have an intimate connection with sustainability as substitutes for fossil energies and as agents for improving energy efficiency. In electrochromic technology, V2O5 is applied as a passive electrode due to its high transmittance and small contrast, and its reversibility on electrochemical reactions. To contribute to increase the optical and charge efficiency of V2O5 thin film passive electrodes, were investigated in this work the influence of the morphological properties, crystallite size and roughness, on the reversible specific charge capacity and the respective optical responses. The films morphological properties were modified by varying their thickness to the nanoscale. The films were deposited by thermal evaporation from powdered V2O5. The crystallite size and surface roughness were measured respectively by XRD and AFM. The results showed that the charge capacity is directly proportional to the surface roughness and inversely proportional to the crystallite size. The film optical contrast and the nominal transmittance shows to be improved according to their morphological properties. In conclusion, the V2O5 opto-electrochemical properties can be improved, increasing the efficiency on the light control processes.
关键词： Thermal evaporation,electrochromism,vanadium oxide,lithium intercalation
更新于2025-09-23 15:21:01
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Undoped p-type BaSi <sub/>2</sub> emitter prepared by thermal evaporation and post-annealing for crystalline silicon heterojunction solar cells
摘要： p-type BaSi2/n-type crystalline Si (p-BaSi2/n-Si) heterojunction solar cells with various BaSi2 thickness (dBaSi2) from 20 to 100 nm were fabricated using a simple preparation method, that is, post-annealing of undoped n-type BaSi2 prepared by thermal evaporation. With decreasing dBaSi2, short-circuit current density increased due to the reduction of the parasitic absorption in p-BaSi2. On the other hand, open-circuit voltage and fill factor decreased due to the increase of the leakage current. As a consequence, the solar cell with dBaSi2 = 80 nm showed a maximum conversion efficiency.
关键词： post-annealing,BaSi2,p-type emitter,heterojunction solar cells,thermal evaporation
更新于2025-09-23 15:19:57
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Development and characterization of TlGaSe2 thin film-based photodetector for visible-light photodetector applications
摘要： In current work a thermal evaporation technique has been employed to fabricate the thin films from the grown TlGaSe2 single crystal and investigated. X-ray diffraction study revealed the formation of polycrystalline films of monoclinic crystal system. The crystallite size was estimated to be 11 nm. Atomic force and scanning electron microscopy studies shows the nanocrystalline film fabrication and the size of grain was estimated. Optical study shows that the grown film is about 55% transparent in 800–1500 nm region and possess a sharp absorption edge. The direct energy gap of TlGaSe2 films was estimated around 2.31 eV. The photo current of the fabricated TlGaSe2 photodetector increases about 6 times compare to dark when exposed under 5 mW/cm2 illumination. The fabricated detector possesses high external quantum efficiency of 158% and also the detectivity reached to 5.16 ? 1010 at V ? 10 V. The on/off behaviour of the device was also studied and found that the response time for growth and decay is 88 ms and 90 ms, respectively.
关键词： A. Thin film,D. optical properties,C. X-ray diffraction,B. thermal evaporation,D. electrical properties,D. photodetector
更新于2025-09-23 15:19:57
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Fabrication and characterization of microcavity organic light-emitting diode with CaF2/ZnS distributed Bragg reflector
摘要： We fabricated alternately multilayered films using CaF2 and ZnS with a different number of pairs by thermal evaporation method and evaluated their reflectance as a distributed Bragg reflector (DBR). A 7-pair CaF2/ZnS multilayered film had an enough high reflectance for use as DBR in the wavelength region of 400–600 nm, which is good agreement with the theoretically calculated reflectance. The fabricated CaF2/ZnS multilayered film was incorporated to the organic light-emitting diode (OLED) devices. We found that the inversed-type OLED (iOLED) structure is suitable for achieving the working device. From the result of electroluminescence (EL) measurement, the spectral linewidth of EL of inversed OLED with DBR (μ-cavity iOLED) was significantly narrowed compared to that of conventional OLED (cOLED). The EL peak wavelength of μ-cavity iOLED was centered around 520 nm, which was well corresponded to the designed cavity length. The observed narrowing of EL spectra for μ-cavity iOLED was originated from the microcavity effect. Color coordinate of the emission were changed from cOLED: (0.31, 0.54) to μ-cavity iOLED (0.20, 0.72), which indicates a significant improvement of color purity of green emission.
关键词： Thermal evaporation,Microcavity effect,Indium-free,Electroluminescence,Color purity
更新于2025-09-19 17:13:59
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Effect of Si substrate modification on improving the crystalline quality, optical and electrical properties of thermally-evaporated BaSi2 thin-films for solar cell applications
摘要： We have grown orthorhombic barium disilicide (BaSi2) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time te on crystalline quality as well as optical and electrical properties of the BaSi2 films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the BaSi2 thin-films. The te of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the BaSi2 film at te of 8 s were 38 mA/cm2, 273 cm2/Vs, and 2.3 μs, respectively. These results confirm that the BaSi2 thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.
关键词： hall mobility,substrate modification,photoresponse,silicide semiconductor,Barium disilicide,minority carrier lifetime,optical property,thermal evaporation
更新于2025-09-19 17:13:59