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.
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.