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Wyszukujesz frazę "Ullah, M." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Effect of Reactor Pressure on Electrical and Structural Properties of Diamond Films Grown by Hot-Filament CVD
Autorzy:
Ullah, M.
Ahmed, E.
Rana, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030224.pdf
Data publikacji:
2017-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
HFCVD
electrical properties
diamond films
growth
reactor pressure
Opis:
Polycrystalline diamond films with preferred (111) and (222) facets were fabricated inside hot filament chemical vapour deposition reactor on silicon wafers using a mixture of 1% methane in hydrogen at various reactor pressures ranging from 10 to 50 mbar. Regarding characterization of diamond films, internal texture, surface morphology, quality of diamond and electrical conductivity were investigated using X-ray diffraction, scanning electron microscopy, the Raman spectroscopy and four-point-probe van der Pauw techniques, respectively. Results of these studies demonstrate that polycrystalline diamond structure is grown in random orientation with (111) facet being dominant showing sharp grain boundaries. Moreover, growth rate was found to increase with pressure up to 20 mbar and then decreased for further rise in pressure. That is why grain density is high with relatively smaller grains at higher pressures caused by higher nucleation rates. In contrast, electrical resistivity decreased ≈3 orders of magnitude showing a minimum at 2.9×10⁶ Ω cm as pressure was increased in the reactor. Reactor pressure during film growth resulted in poor surface morphology, absence of sp³ bonds and low resistivity. Hence, decrease of resistivity makes diamond films desirable for many electrical applications in semiconducting/electronic devices.
Źródło:
Acta Physica Polonica A; 2017, 131, 6; 1419-1425
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Theoretical Study of Magnetic Behavior of Diamond Doped with Transition Metals
Autorzy:
Hussain, F.
Ullah, M.
Ullah, H.
Rashid, M.
Imran, M.
Ahmad, E.
Powiązania:
https://bibliotekanauki.pl/articles/1399279.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Kt
75.10.Pq
75.30.Hx
Opis:
We study the magnetic behavior of the diamond system. In this system diamond bulk is involved which is doped with different transition metals, namely Cu, Cd, Hg, and Zn. The VASP code is employed for all calculations which are based on density functional theory. The substitutional point defects is introduced in the diamond bulk and occupied by the transition metals. Results exhibit that all transition metals show ferromagnetism behavior and Cu is a good advocate of conductivity among all transition metals. The range of magnetic moments is 2.89, 1.99, 1.96, and 1.80 $μ_{B}$ per Cu, Cd, Hg, and Zn atom in diamond bulk, respectively. Strong magnetic behavior points out that these materials could be used for spintronics.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 823-826
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solitons in Nonlinear Directional Couplers with Optical Metamaterials by Trial Function Scheme
Autorzy:
Arnous, A.
Ekici, M.
Moshokoa, S.
Zaka Ullah, M.
Biswas, A.
Belic, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032564.pdf
Data publikacji:
2017-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Dp
42.65.Tg
Opis:
This paper obtains soliton solutions to nonlinear directional couplers in optical metamaterials by the aid of trial function method. Three types of couplers are studied. Four forms of nonlinearity are considered. Bright, dark, and singular soliton solutions are retrieved. These soliton solutions appear with certain constraint conditions that guarantee their existence.
Źródło:
Acta Physica Polonica A; 2017, 132, 4; 1399-1410
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Embedded Solitons and Conservation Law with $χ^{(2)}$ and $χ^{(3)}$ Nonlinear Susceptibilities
Autorzy:
Savescu, M.
Kara, A.
Kumar, S.
Krishnan, E.
Zaka Ullah, M.
Moshokoa, S.
Zhou, Qin
Biswas, A.
Powiązania:
https://bibliotekanauki.pl/articles/1398312.pdf
Data publikacji:
2017-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
solitons
χ^{(2)}
conservation laws
Opis:
This paper studies embedded solitons that are confined to continuous spectrum, with $χ^{(2)}$ and $χ^{(3)}$ nonlinear susceptibilities. Bright and singular soliton solutions are obtained by the method of undetermined coefficients. Subsequently, the Lie symmetry analysis and mapping method retrieves additional solutions to the model such as shock waves, singular solitons, cnoidal waves, and several others. Finally, a conservation law for this model is secured through the Lie symmetry analysis.
Źródło:
Acta Physica Polonica A; 2017, 131, 2; 297-303
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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