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M.S. Jagadeesh

Bio: M.S. Jagadeesh is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Thin film & Electrical resistivity and conductivity. The author has an hindex of 5, co-authored 7 publications receiving 85 citations.

Papers
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TL;DR: The growth of defects in vacuum-evaporated MoO3 films has been studied by optical absorption in the present work as discussed by the authors, where as-grown films were subjected to different kinds of treatment such as thermal annealing, UV and X-ray irradiation, and their optical absorption spectra were recorded between 300 and 1500 nm at room temperature as well as at liquid N2 temperature.
Abstract: The growth of defects in vacuum-evaporated MoO3 films has been studied by optical absorption in the present work. The as-grown films were subjected to different kinds of treatment such as thermal annealing, UV and X-ray irradiation, and their optical absorption spectra were recorded between 300 and 1500 nm at room temperature as well as at liquid N2 temperature The films were found to be amorphous from X-ray and electron-microscopic studies. From these studies it is observed that in addition to point defects, defect aggregates similar to the colloidal centres in silver and alkali halides, are present in these films.

26 citations

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TL;DR: In this article, the initial lattice distortion energy spectra of the films have been determined from the resistance-temperature data, and it is found that the resistivity values for films of different thicknesses are in good agreement with the size effect theory.

23 citations

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TL;DR: In this paper, the initial lattice distortion energy spectra of SnSb thin films of the same thickness (600 A) vacuum deposited at room temperature on glass substrates at various deposition rates were heated to a maximum temperature of about 300°C and the changes in the electrical resistance with temperature were recorded.

12 citations

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TL;DR: In this paper, electrical resistivity and Hall effect measurements have been made on vacuum evaporated Bi 90 Sb 10 alloy films of various thickness (350 A to 4500 A), in the temperature range of 77 to 510 K.

10 citations

Journal ArticleDOI
TL;DR: In this article, the electric resistivity and Hall effect were studied for the vacuum evaporated and annealed ∠1 at.% Sb-doped bismuth alloy films of various thickness (350-3500 A) in the temperature range of 77-510 K.
Abstract: The electric resistivity and Hall effect were studied for the vacuum evaporated and annealed ∠1 at.% Sb‐doped bismuth alloy films of various thickness (350–3500 A) in the temperature range of 77–510 K. Contrary to the behavior of bulk BiSb alloy, where the alloy becomes semiconducting only at about 4 at.% of Sb and above (A.L. Jain, 1959), it is found that thin films of 1% Sb‐doped Bi alloy are semiconducting. Moreover, this semiconducting trend begins at about room temperature unlike in bulk BiSb alloys where it is observed only at temperatures below about 180 K. The present type of behavior has been predicted and observed by some earlier workers (Ivanov et al. 1963, 1964). The intercrystalline barrier activation energies determined for various film thicknesses deposited at different substrate temperatures (257 K, 300 K, 373 K) were found to vary with thickness and substrate temperature, activation energy decreasing with increasing thickness and substrate temperature. These observations have been attribu...

10 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the progress in all of these areas will be reviewed thoroughly, including the early stage of the research, the band structure, photochromic mechanism and the behavior of the oxide.
Abstract: Molybdenum oxide can exhibit pronounced photochromism and thus might act as an excellent photonic material for a number of technical applications. In the early stage of the research, the attention was focused mainly on the (band) structure, photochromic mechanism and the behavior of the oxide. Later, many investigations were carried out on the factors that might influence the photochromic performance. At the same time, the photochromic response has been extended from UV light to visible light. In this review, the progress in all of these areas will be reviewed thoroughly.

258 citations

Journal ArticleDOI
P.F. Carcia1, E.M. McCarron1
TL;DR: In this paper, thin film polymorphs of molybdenum trioxide have been synthesized by reactive r.f. sputtering in an atmosphere of argon plus oxygen.

162 citations

Journal ArticleDOI
TL;DR: In this paper, the properties of rf-sputtered molybdenum oxide films for electrochromic display devices have been investigated, and the dependence of the properties on the oxygen concentration in the sputtering atmosphere was mainly concerned.
Abstract: Properties of rf‐sputtered molybdenum oxide films for electrochromic display devices have been investigated. This report mainly concerns the dependence of the properties on the oxygen concentration in the sputtering atmosphere. The oxide films were prepared by rf sputtering from a compressed powder MoO3 target under an operating pressure of 4×10−2 Torr using a mixture of Ar‐0.5–50% O2. Electrical resistivity of the films formed increases with increasing oxygen concentration in the sputtering atmosphere and ranges from 2.5×1010 to ∼1×1012 Ω cm. Spectral transmittance of the films is about 85% in the visible and near‐infrared region. Optical band gap and refractive index of these films are 2.67–2.76 eV and 2.01–2.26, respectively. Electrochemichromic properties of the films were also studied using asymmetric cells, and it was found that a good electrochromic performance was obtained usually by the cells composed of the films with a resistivity of 2.5×1010 Ω cm.

109 citations

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TL;DR: Molybdenum oxide thin films find diverse applications as catalysts, gas sensors, and electrochromic devices as mentioned in this paper, and are produced mainly by reactive sputtering and thermal evaporation but other...
Abstract: Molybdenum oxide thin films find diverse applications as catalysts, gas sensors, and electrochromic devices. Such films are produced mainly by reactive sputtering and thermal evaporation but other ...

91 citations

Journal ArticleDOI
TL;DR: In this article, the optical properties of slightly blue molybdenum trioxide thin films were investigated with a view to phonon and polaron species and temperature-dependent change in the optical band gap has also been interpreted in terms of band gap slope, B, and the real part of the refractive index, n.
Abstract: Heating and annealing effects on the optical properties of slightly blue substoichiometric molybdenum trioxide thin films are reported partially. During heating and annealing, different levels of coloration seem to be generated by simultaneous reduction and proton injection into thin films, which cause the formation of hydrogen molybdenum bronzes of different concentrations. The optical band gap, Eo, of MoO3 thin film when annealed in between 313 and 473 K is decreased to 2.82 eV, and this reduction in Eo has been explained with a view to phonon and polaron species. Moreover, temperature-dependent change in the optical band gap has also been interpreted in terms of band gap slope, B, and the real part of the refractive index, n. Urbach slope, σ, also goes down to 0.67 eV−1 due to annealing treatment. Using the oscillator model, a phonon energy, hνo, of about 0.08 eV was found for the reported MoO3 thin film which is very close to the characteristic phonon energy of MoO3. Over and above, the intensity for the blue absorption band, over the photon energy range 0.4–3.0 eV, also reaches a maximum as MoO3 thin film is annealed at 473 K for 1 h and then decreases by 32% after annealing at the same temperature for 2 h. This phenomenon is due to polaronic band intensity which rises and falls during annealing. Half-width of the blue band, as found by fitting polaron model, is changed only by 3% on annealing the MoO3 thin film at 473 K as compared to its value at room temperature.

86 citations