Satyabrata Mohapatra
Volume 8, Issue 10 , October 2017, , Pages 999-1003
Abstract
We report on the gettering behavior of Au at end-of-range (EOR) defects in float-zone grown Si(111), implanted with 1.5 MeV Au 2+ ions at room temperature. The effects of implantation dose and annealing temperature on the thermal evolution of gettering behavior of EOR defects have been investigated using ...
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We report on the gettering behavior of Au at end-of-range (EOR) defects in float-zone grown Si(111), implanted with 1.5 MeV Au 2+ ions at room temperature. The effects of implantation dose and annealing temperature on the thermal evolution of gettering behavior of EOR defects have been investigated using Rutherford backscattering spectrometry, while the microstructural evolution of Au implanted Si(111) has been studied using cross-sectional transmission electron microscopy combined with high resolution transmission electron microscopy. The gettering efficiency of EOR defects, comprising of dislocation loops, has been found to increase with increase in implantation dose up to 1.2 x 10 15 ions cm -2 , beyond which it was found to saturate at about 5 x 10 14 atoms cm -2 for annealing at 850 o C. We have observed that the gettering efficiency of the EOR defects for Au increased with increase in annealing temperature and reached 9 x 10 14 atoms cm -2 for annealing at 950 o C. The observed enhanced gettering efficiency of EOR defects is very promising for gettering applications in Si devices.
Shrabani Mondal; Rashmi Madhuri; Prashant K. Sharma
Volume 8, Issue 9 , September 2017, , Pages 927-931
Abstract
This letter assesses the origin of linear and planer micro-structural defects in SnO2 nanoparticles through high resolution transmission electron microscopy (HRTEM). For the purpose, SnO2 nanoparticles of size 5-15 nm are synthesized by chemical co-precipitation followed by calcinations. In the low temperature ...
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This letter assesses the origin of linear and planer micro-structural defects in SnO2 nanoparticles through high resolution transmission electron microscopy (HRTEM). For the purpose, SnO2 nanoparticles of size 5-15 nm are synthesized by chemical co-precipitation followed by calcinations. In the low temperature (200°C and 400°C) calcinations range no significant evidence of micro-structural defect are observed. Whereas, SnO2 nanoparticles calcined at 600°C shows better crystallinity with multiple 1-D linear defects along with 2-D planer defects. Contribution of size and strain effect causing such circumstances is illustrated in detail. Influence of these micro-structural defects on the luminescence properties of SnO2 nanoparticles is also elaborated in detail.
Kuldeep Chand Verma; R.K. Kotnala
Volume 7, Issue 8 , August 2016, , Pages 622-629
Abstract
We reported the Core/Shell structures of CoFe2-xCexO4 (CFCeO) nanoparticles were prepared by a chemical combustion method. The Rietveld refinement of X-ray diffraction pattern results into CoFe2O4 spinel structure and thevariation in lattice parameters have been found with doping of Ce ions. Transmission ...
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We reported the Core/Shell structures of CoFe2-xCexO4 (CFCeO) nanoparticles were prepared by a chemical combustion method. The Rietveld refinement of X-ray diffraction pattern results into CoFe2O4 spinel structure and thevariation in lattice parameters have been found with doping of Ce ions. Transmission Electron Microscopy analysis has shown Core/Shell type nanoparticles. The stoichiometric composition of Co, Fe, Ce and O atoms has been analyzed through X-ray fluorescence elemental detection. Fourier transform infrared spectra could detect organic extent, tetrahedral (Fe-O), octahedral (Fe(Ce)-O-Co) and lattice disorder in CFO nanoparticles with Ce doping. Defects related oxygen vacancies are analyzed in Photoluminescence emission spectra. The room temperature magnetic measurement of CFO nanoparticles is highly influenced with Ce ions. The magnetic interactions are antiferromagnetic at room temperature that confirmed by zero field cooling and field cooling magnetic measurements at 100 Oe. However, the spin glass and ferromagnetic clustered growth may also exist in CFCeO samples that reduce room temperature ferromagnetism. The dielectric measurement indicates polarization up to higher frequency region that enhanced with Ce ions.
Nadarajah Muhunthan; Om P. Singh; Vidya N. Singh; Kedar N. Sood
Volume 6, Issue 4 , April 2015, , Pages 290-293
Abstract
Copper zinc tin sulfide (CZTS) thin film was deposited by co-sputtering metal targets and post-deposition sulfurization in H2S. Temperature-dependent electrical conductivity and photoconductivity effects in CZTS are studied. The low temperature electrical conductivity measurement shows acceptor level ...
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Copper zinc tin sulfide (CZTS) thin film was deposited by co-sputtering metal targets and post-deposition sulfurization in H2S. Temperature-dependent electrical conductivity and photoconductivity effects in CZTS are studied. The low temperature electrical conductivity measurement shows acceptor level energy value as 36.85 meV. A large decay time of 108 s at 300K, 99 s at 200K and 94 s at 100K after switching off the light source was observed. The decay behavior of this persistent photoconductivity (PPC) in CZTS follows the double exponential function. The results show that defects are responsible for the observed PPC in CZTS. The combined measurements of low temperature electrical conductivity and photoconductivity give account of the defect level. Control of these defects can improve the quality of material and thus the resulting device.
S. Pal; A. Sarkar; D. Sanyal; T. Rakshit; D. Kanjilal; P. Kumar; S. K. Ray; D. Jana
Volume 6, Issue 4 , April 2015, , Pages 365-369
Abstract
1.2 MeV Argon (Ar) ion irradiation turns white coloured ZnO to yellowish (fluence 1 × 10 14 ions/cm 2 ) and then reddish brown (1 × 10 14 ions/cm 2 ). At the same time the material becomes much more conducting and purely blue luminescent for the highest fluence of irradiation. To get ...
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1.2 MeV Argon (Ar) ion irradiation turns white coloured ZnO to yellowish (fluence 1 × 10 14 ions/cm 2 ) and then reddish brown (1 × 10 14 ions/cm 2 ). At the same time the material becomes much more conducting and purely blue luminescent for the highest fluence of irradiation. To get insight on the defects in the irradiated samples Ultraviolet-visible (UV-vis) absorption, Raman, and photoluminescence (PL) spectroscopy and Glancing Angle X-Ray Diffraction (GAXRD) measurements have been carried out. Enhancement of overall disorder in the irradiated samples is reflected from the GAXRD peak broadening. UV-vis absorption spectra of the samples shows new absorption bands due to irradiation. Complete absorption in the blue region of the spectrum and partial absorption in the green and red region changes the sample colour from white to reddish brown. The Raman peak representing wurtzite structure of the ZnO material (~ 437 cm -1 ) has decreased monotonically with the increase of irradiation fluence. At the same time, evolution of the 575 cm -1 Raman mode in the irradiated samples shows the increase of oxygen deficient disorder like zinc interstitials (IZn) and/or oxygen vacancies (VO) in ZnO. PL spectrum of the yellow coloured sample shows large reduction of overall luminescence compared to the unirradiated one. Further increase of fluence causes an increase of luminescence in the blue region of the spectrum. The blue-violet emission can be associated with the interstitial Zn (IZn) related optical transition. The results altogether indicates IZn type defects in the highest fluence irradiated sample. Large changes in the electrical resistance and luminescent features of ZnO using Ar ion beam provides a purposeful way to tune the optoelectronic properties of ZnO based devices.
