Ramakanta Naik; C. Sripan; R. Ganesan
Abstract
In this manuscript, the As40Se60 and As50Se50 samples of 800nm thickness were deposited onto glass substrate by thermal evaporation technique. The as-deposited films were characterized using X-ray diffraction (XRD) and FTIR Spectrophotometer. The prepared samples are amorphous type. The transmission ...
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In this manuscript, the As40Se60 and As50Se50 samples of 800nm thickness were deposited onto glass substrate by thermal evaporation technique. The as-deposited films were characterized using X-ray diffraction (XRD) and FTIR Spectrophotometer. The prepared samples are amorphous type. The transmission is found to be decreased for As50Se50 film. The indirect optical transition mechanism for the photon absorption happens inside the studied film. The optical band gap is decreased with change in As and Se content. The density of state model and increase in disorder is responsible for the reduction of optical band gap in the studied films. The addition of more % As creates localised states in the gap which results the tailing of the band edges. The Urbach energy which gives the degree of disorder changes that indicates the more disorderness of As50Se50 than As40Se60 film. The XPS As3d, Se3d core level spectra variation infers the optical changes in the film and such type of film can be used for optical materials and optoelectronics.
Pawan Kumar; Amit Sanger; Arvind Kumar; Davinder Kaur; Ramesh Chandra
Abstract
In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of ...
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In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of the CZO thin films on the carbon monoxide (CO) gas sensing performance have been examined. Fast response time (47 sec) and an optimum recovery time (~ 86 sec) have been witnessed at an adequate temperature of 250°C for the samples having contact angle ~ 131o and surface roughness ~ 14.86 nm. Hydrophobicity of the surface provides short recovery time by opposing the existence of water-vapour on the surface. Copyright © 2018 VBRI Press.
Bhishma Karki; Jeevan Jyoti Nakarmi; Rhiddi Bir singh; Manish Banerjee
Abstract
The influence of Au doping in ZnO thin films was studied with respect to photoelectrocatalytic degradation of methylene blue (MB). Influence of Au doping concentration onto PEC structural morphological, optical and luminescence properties of the ZnO thin films were thoroughly investigated. The maximum ...
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The influence of Au doping in ZnO thin films was studied with respect to photoelectrocatalytic degradation of methylene blue (MB). Influence of Au doping concentration onto PEC structural morphological, optical and luminescence properties of the ZnO thin films were thoroughly investigated. The maximum value of Isc and Voc for 3 at. % Au:ZnO thin films confirms the optimization of doping percentage. XRD and SEM were used to study the structure and morphology of the films. Films were nanocrystalline and exhibit a hexagonal crystal structure with no additional phases of gold compounds. For degradation of MB, Au:ZnO films were used as photoelectrode, it was observed that due to Au:ZnO 80% degradation of MB occurs in 150 min. Moreover, large area (100 cm2) Au doped ZnO thin films have been prepared on FTO coated glasses (10–15 Ω). Photocorrosion of ZnO electrode was examined by atomic absorption spectroscopy and no zinc was observed in AAS measurement. Copyright © 2017 VBRI Press.
Nagendra Vara Prasad M; Jeevan Kumar R; Munikrishna Reddy Y
Abstract
In the present work, Ag2O films are deposited at room temperature using DCMS (Magnetron Sputtering) method with the variation of pressure of O2 during the development of film. The pressure of O2 in the DCMS unit chamber is arranged between 2X10-2 and 6X10-2 Pa. Transmission and absorption spectrum are ...
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In the present work, Ag2O films are deposited at room temperature using DCMS (Magnetron Sputtering) method with the variation of pressure of O2 during the development of film. The pressure of O2 in the DCMS unit chamber is arranged between 2X10-2 and 6X10-2 Pa. Transmission and absorption spectrum are recorded to assess the impact of increasing thickness on certain optical parameters such as indirect band gap, direct band gap, dielectric constant etc. As O2 pressure is varies between 2X10-2 Pa and 6X10-2 Pa, optical energy band gap shows a decreasing trend between 1.041 eV and 0.942 eV. It is also observed that the absorption transmittance of the deposited films increases with the increase of thickness of the film. This way, the study reveals that all the parameters are affected by varying pressure of O2. The effective useful of theseO2-rich films is also discussed keeping in view the increasing importance of the modern technological applications such as photovoltaic cell fabrication. Thus, this technique can also be applied to produce films using other metal oxides. Copyright © 2017 VBRI Press.
Mukesh Kumar; Neelam Kumari; Vinod Karar; Amit L Sharma
Abstract
HfO2 thin films have gained much significance in recent years as a promising dielectric material for semiconductor electronics added to their wide applications in the field of optical filters as a high index material. The resistance of HfO2 films to impurity diffusion and intermixing at the interface ...
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HfO2 thin films have gained much significance in recent years as a promising dielectric material for semiconductor electronics added to their wide applications in the field of optical filters as a high index material. The resistance of HfO2 films to impurity diffusion and intermixing at the interface as well as higher environmental stability have made these films one of the most extensively studied upon materials in laser optics, optical coatings and semiconductor domain. In the present study, Hafnium Oxide film was deposited on glass substrate using reactive oxygenated E-Beam deposition technique with in-situ quartz crystal thickness monitoring to control the film thickness and rate of evaporation. The coated substrate was optically characterized using spectrophotometer and Variable Angle Spectroscopic Ellipsometry (VASE) to determine its transmission spectra as well as optical constants. The coated sample was put under thermal stress testing in a test chamber with temperature variation from -40° to + 65° C in a cyclic manner for 7 cycles with a rate of temperature change of 5° C/minute. The coated sample was again optically characterized to investigate the effect of thermal cycling on its optical performance and physical parameters. Copyright © 2017 VBRI Press.
Sharmistha Anwar; Barada K. Mishra; Shahid Anwar
Abstract
Thermoelectric thin films of Bi2Te3 and Sb2Te3 were deposited by using sputtering technique. Structural characterizations of as deposited films were done by using X-ray diffraction (XRD), Energy Dispersive X-ray Analysis and electrical properties have been evaluated at room temperature by Seebeck coefficient ...
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Thermoelectric thin films of Bi2Te3 and Sb2Te3 were deposited by using sputtering technique. Structural characterizations of as deposited films were done by using X-ray diffraction (XRD), Energy Dispersive X-ray Analysis and electrical properties have been evaluated at room temperature by Seebeck coefficient and electrical resistivity measurement. These sputtered films were established to be polycrystalline and of desired single phase in nature with stoichiometric composition. The Seebeck coefficient and electrical resistivity of p-type Sb2Te3 thin film and n-type Bi2Te3 thin films were found to be about 111 μV/K, 8.25×10-5 Ω- m and −98.52μV/K, 5.87×10-6 Ω-m, respectively whereas to that of n-type Bi2Te3-Sb2Te3 multilayer having 5BL combination is −145μV/K, 9.31×10-5 Ω-m and 10BLcombination is −170 μV/K, 9.86×10-5 Ω-m. The power factor value has increased reasonably well in case of multilayer as compared to that of individual single layer, maximum power factor value 2.95×10-3 W/m K2 has been achieved for 10BL combination. These results indicate that good quality antimony telluride, bismuth telluride and their multilayer thin films can be grown easily by using sputtering technique. It also suggests that these types of nano-structuring (multilayer structure) in these categories of materials can be promissory engineering concept for the fabrication of micro-Peltier modules.
Mukta Behera; Rozalin Panda; Naresh C. Mishra; Ramakanta Naik
Abstract
In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 ...
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In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 in bulk prepared by melt quenching technique. Bi incorporation in As40Se60 with composition Bi15As40Se45 however led to nucleation of Bi2Se3 nanocrystallites in the amorphous matrix of As40Se60. The films made out of the two targets of composition As40Se60 and As40Bi15Se45 did not show any XRD peak, indicating their amorphous nature. UV-Visible-NIR spectroscopic study indicated a large decrease in the electronic band gap from 1.74 eV in films of composition As40Se60 to 1.28 eV for compositon Bi15As40Se45. This decrease is explained on the basis of a high concentration of defect states leading to the presence of localized states in the band gap due to Bi incorporation. Field emission scanning electron microscopy (FESEM) images show smooth and homogeneous surface for the As40Se60 films, while Bi incorporation led to increases of the surface roughness in the Bi15As40Se45 films. The decreased band gap and increased surface roughness on Bi incorporation in As40Se60 films indicate the suitability of these films for solar cell applications.
