R Subba Reddy; S Uthanna; A Sivasankar Reddy; T. Srikanth; B. Radha Krishna
Abstract
Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 ...
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Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 nm /min with increase of oxygen partial pressures. X- ray diffraction results reveal that the films deposited at oxygen partial pressure of 2x10-2 Pa the (100) preferred orientation peak crystallinity became better. Raman spectroscopy analysis shows an improvement in the crystalline quality of the films at 2x10-2 Pa. Fourier transform infrared spectroscopy of ZnO films confirms the presence Zn-O bonding. The nanorods were observed at oxygen partial pressure of 5x10-2 Pa. The maximum transmittance of 97% and crystallite size of 21 nm was observed at oxygen partial pressure of 2x10-2 Pa. The as deposited films annealed at 473 K the intensity of (100) phase was decreased. The RMS roughness of the as deposited ZnO films was 7.3 nm, and it increased to 30 nm for the films annealed at 473K. Optical spectra revealed the films annealed at 673 K show the optical band gap of 3.17 eV. Copyright © 2018 VBRI Press.
Indu B. Vashistha; Mahesh C. Sharma; S.K. Sharma
Abstract
In this present study Cu2ZnSnS4 (CZTS) thin films were grown by Chemical Bath Deposition (CBD) method at optimized parameters. These as grown CZTS films were annealed at 3000C for different time 1 hr, 2 hr, 3 hr. These films were characterized by scanning electron microscope (SEM), UV-VIS Spectrophotometer, ...
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In this present study Cu2ZnSnS4 (CZTS) thin films were grown by Chemical Bath Deposition (CBD) method at optimized parameters. These as grown CZTS films were annealed at 3000C for different time 1 hr, 2 hr, 3 hr. These films were characterized by scanning electron microscope (SEM), UV-VIS Spectrophotometer, I-V measurement for study of surface morphology, optical and electrical properties respectively. The SEM analysis revealed that surface modification takes place as the annealing time increases. The optical study shows high absorption in visible region and as annealing time increase red shift in energy band gap occurred. The current-voltage characteristics of the specimen indicated that conductivity of film increases with increased annealing time. Thus, annealing time has prominent impact on surface modification which changes optoelectronic properties of CZTS thin film and results shows that film annealed at 3000C for 3 hr gives high absorption and better conductivity for CZTS thin films. Copyright © 2018 VBRI Press.
Narendra Singh; Davinder Kaur
Abstract
Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray ...
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Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and photospectrometer respectively. X-ray diffraction pattern revealed (102) and dominant (105) reflections which corresponds to 4H-SiC and an enhancement in (105) peak intensity with increasing thickness was also observed. The thickness measured by X-ray reflectometry (XRR) reduces from ~ 46 nm to 12 nm by decreasing deposition time (40-10 minute) which in turn reduces the crystallite size. Photoluminescence spectra show a broad peak extending from ultraviolet to blue region centered at ~ 385 nm for film of thickness ~ 46 nm (deposition time 40 min). A shifting in Photoluminescence peak towards shorter wavelength (blue shift) with decreasing SiC ultrathin film thickness was observed, which could be attributed to quantum confinement effect. The improved Photoluminescence in ultrathin nanocrystalline SiC films could make it a potential candidate in optoelectronic and biomedical applications. Copyright © 2017 VBRI Press.
Mohd A. Ansari; Daipayan Dasgupta; K. Sreenivas
Abstract
Ultraviolet (UV) light detection characteristics with sputtered ZnO films deposited on paper with graphite pencil drawn conducting inter-digital electrodes on normal paper have been investigated. Structural, electrical and microstructural properties of ZnO films grown by magnetron sputtering ...
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Ultraviolet (UV) light detection characteristics with sputtered ZnO films deposited on paper with graphite pencil drawn conducting inter-digital electrodes on normal paper have been investigated. Structural, electrical and microstructural properties of ZnO films grown by magnetron sputtering technique at under differentsputtering pressures have been evaluated forultraviolet (UV) light detection. Different types of paper used as substrate material, and the influence of their surface microstructure on the growth of ZnO film quality is examined.Films deposited on the fibrous paper are found to be polycrystalline, whereas the same films on dense glass substrates promote a c-axis oriented growth. The nucleation of sputtered ZnO films on paper is found to occur along the fine fibers of the paper and vary with sputtering pressure. Films grown at higher sputtering pressures (30 to 40 mTorr) in Ar/O2=50:50 are found to yield dense deposits. Pencil drawn inter- digital electrode structures on paper overlaid with 0.25 μm thick ZnO films exhibit reproducible photo response to ultraviolet (UV) light (= 365 nm), with low dark current. It’simportant for low prize and easy fabrication of optoelectronic foldable devices.Copyright © 2017VBRI Press
Vinod Karar; Amit L Sharma
Abstract
Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being ...
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Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being reflected and transmitted by various interfaces where it is split by percentage of overall intensity or wavelength. In this study, design and fabrication of a dichroic optical beam splitter for filtering of red and green light from a white light source has been presented. Here, a symmetric dielectric multilayer stack with 15 alternating layers of alumina and silica are deposited on BK-7 glass using e-beam evaporation technique. High and low refractive indices of 1.63 and 1.46 respectively are used with quarter-wave optical thicknesses of layers. The beam splitter is designed for 45 ̊ angle of incidence using FilmstarTM design software. Transmission spectrum obtained from UV-Vis-NIR double beam spectrophotometer shows reflectance of ~54% at 660 nm (red wavelength region) and transmittance of ~88% at 550 nm (green wavelength region). The coated sample is further subjected to adhesion and hardness test according to MIL standard and no peel off or scratch is observed indicating excellent durability of the coating. The modelled and measured results closely agree with one another over visible spectral regions. Copyright © 2017 VBRI Press.
Ramakanth Illa; Jaroslav Hamrle; Jaromir Pištora
Abstract
Nanostructured thin films of MnFe2O4 were fabricated using chemical approach. Structural, magnetic, optical and magneto-optical properties of the films have been investigated using XRD, AFM, VSM, spectroscopic ellipsometry and MOKE spectroscopy. Structural evaluation of the thermally annealed films showed ...
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Nanostructured thin films of MnFe2O4 were fabricated using chemical approach. Structural, magnetic, optical and magneto-optical properties of the films have been investigated using XRD, AFM, VSM, spectroscopic ellipsometry and MOKE spectroscopy. Structural evaluation of the thermally annealed films showed crystalline phase and spinel structure along with appearance of textured nano-crystallites at the annealing temperature (Ta) of 500 °C and above. Surface morphology of the films annealed at 600 oC was characterized using AFM and the size of MnFe2O4 particles was observed to be 70 – 180 nm with ellipsoidal morphology and the surface roughness was found to be 8 nm. Hysteresis loops of the ferrite films indicated ferromagnetic behavior for annealing temperature of 400 oC and above, with a small contribution of paramagnetic nature arising from its oxide. The films showed a semiconducting behavior for the annealing temperature (Ta) ranging from 400 - 600 oC. The magneto-optical response is found to be small, i.e., one order less when compared to CoFe2O4 or metallic Fe, Co films. The maximum magneto-optical response from MnFe2O4 thin films is found for Ta = 400 oC, i.e. for incomplete spinel structure. As the material used for making the thin film coating is of the order of very few milligrams, these highly responsive films could be used as magnetic sensors. Copyright © 2017 VBRI Press.
Rashmi Singh; Puneet Jain; Naresh Kumar; Pramod Kumar
Abstract
Thin films of Co2MnSi are grown on n-doped Si (100) and SiO2 (100) substrates by RF sputtering. The deposition time to grow the films is varied, once for ten minutes and another for an hour at a particular substrate temperature 600oC and keeping all the other parameters same. The Co2MnSi thin films deposited ...
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Thin films of Co2MnSi are grown on n-doped Si (100) and SiO2 (100) substrates by RF sputtering. The deposition time to grow the films is varied, once for ten minutes and another for an hour at a particular substrate temperature 600oC and keeping all the other parameters same. The Co2MnSi thin films deposited on Si and SiO2 are crystalline irrespective of the deposition time. The grains were round in the thin films deposited for 10 minutes and these grains are more consistently interconnected in the films deposited for 1 hour. This is supported by the surface roughness data from AFM. The rms roughness is found to be 4.82nm for Si for 10 minutes and 2.50nm for Si for 1 hour deposition that was observed over an area of 3µm2. Copyright © 2017 VBRI Press.
Kirandeep Singh; Shuvam Pawar; Davinder Kaur
Abstract
Silicon integrated vertically aligned Ni-Mn-In nanorod arrays having ~100 nm length were investigated for shape memory behavior and magnetocaloric effect. The room temperature X-ray diffraction (XRD) patterns revealed the (220) oriented pure austenitic cubic phase growth of Ni–Mn–In nanorods. ...
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Silicon integrated vertically aligned Ni-Mn-In nanorod arrays having ~100 nm length were investigated for shape memory behavior and magnetocaloric effect. The room temperature X-ray diffraction (XRD) patterns revealed the (220) oriented pure austenitic cubic phase growth of Ni–Mn–In nanorods. The systematic thermo-magnetic (M-T) plots, resistance vs. temperature (R-T) measurements, as well as the negative slope of Arrott plots (H/M vs. M2) curves revealed the existence of significant shape memory effect in 100 nm Ni-Mn-In rods between 230 ≤ T≤ 294 K region. The formation of narrow hysteresis between field cooled (FC) and field warm (FW) curves in contrast to previous studies which reported broadness in the martensitic transformation temperature regime with decreasing thickness [1], can be ascribed to reduced substrate clamping effect due to vertically aligned growth of Ni-Mn-In. The magnetocaloric curves evaluated from M-H study indicates that large magnetic field magnitude dependent entropy change occurs in Ni-Mn-In rods, a maximum attainable ΔSM ~ 0.4 mJ/cc.K was observed at 275 K. Such vertically aligned growth of Ferromagnetic Shape Memory Alloys (FSMA’s) thin films over semiconductor substrate exhibiting significant shape memory behavior could prove useful in many MEMS/NEMS applications as well as opens possibility of futuristic self-cooled spintronics devices like magneto-electric random access memory (ME-RAM). Copyright © 2016 VBRI Press.
P. Rosaiah; G. Lakshmi Sandhya; S. Suresh; Jinghui Zhu; Yejun Qiu; O. M. Hussain
Abstract
Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the ...
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Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the films prepared at lower temperatures are amorphous in nature and the films prepared at 300 oC is exhibited predominant (001) orientation with an orthorhombic crystal structure. AFM study showed that the grain size varies from 80 nm to 150 nm. The optical studies revealed that the transmittance decreased with increasing substrate temperature. The optical absorption coefficient ‘a’ determined from the experimentally measured transmittance and reflectance data for V2O5 films was found to give a better fit for the exponent n = 3/2 suggesting the direct forbidden transitions with an estimated optical band gap of 2.31 eV for the films prepared at 300 oC. The electrical conductivity has been observed to be increased from 2 x 10-6 S/cm to 3 x 10-2 S/cm by varying temperature from 30 oC to 300 oC. The electrochemical experiments exhibited the discharge capacity of about 60 μAh/(cm2-μm) for the films deposited at 300 oC.
