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Sikander Azam,Saleem Ayaz Khan,Jan Minar,Souraya Goumri-Said 한국물리학회 2015 Current Applied Physics Vol.15 No.10
Due to growing demand on discovering new materials for light-emitting diodes devices, many efforts were made to discover and characterize new inorganic materials such as phosphors. Using the full potential method within density functional theory the electronic and optical properties of BaAl2Si3O4N4 and BaAlSi4O3N5 semiconductors have been investigated. The electronic structure and the optical properties of these phosphors were calculated through a reliable approach of modified Beck-Johnson (mBJ) approach. We found that BaAl2Si3O4N4 and BaAlSi4O3N5 have wide direct band gaps positioned at G about 5.846 and 4.96 eV respectively. The optical properties, namely the dielectric function, optical reflectivity, refractive index and electron energy loss, are reported for radiation up to 15 eV. Our study suggests that BaAl2Si3O4N4 and BaAlSi4O3N5 could be promising materials for applications in the LEDs devices and optoelectronics areas of research.
Fahad Ali Shah,Saleem Ayaz Khan,Suneela Arif,Sikander Azam,R. Khenata,S. Bin Omran 한국물리학회 2015 Current Applied Physics Vol.15 No.5
The state-of-the-art all-electron FLPAW method and the BoltzTrap software package based on semiclassical theory were adopted to explore the electronic structure and the optical and thermoelectric properties of Ga1-xInxN. Ga1-xInxN is predicted to be a direct band gap material for all values of x. Moreover, the band gap varies between 2.99 eV and 1.95 eV as x changes. Optical parameters such as the dielectric constant, absorption coefficient, reflectivity and refractive index are calculated and discussed in detail. The doping of In plays an important role in the modulation of the optical constants. The static dielectric constant ε (0) of Ga1-xInxN was calculated as 3.95, 3.99, 3.99 and 4.03 at x = 0.00, 0.25, 0.50 and 0.75, respectively. The static refractive index is 2.0 for pure Ga1-xInxN at x = 0.00. The thermal properties varied greatly as x fluctuated. The ternary alloy has large values for the Seebeck coefficient and figure of merit at high temperatures and is thus suitable for thermoelectric applications. Pure Ga1-xInxN at x = 0 exhibited ZT = 0.80 at room temperature, and at higher temperatures, the thermal conductivity decreased with increased In doping.
Madiha Makhdoom,Muhammad Imran Jamil,Sikander Azam,Muhammad Irfan,Zeesham Abbas,Banat Gul,Saleem Ayaz Khan,Xiaotian Wang 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.12
A hydrogen storage material can also be used as a potential and effective solid reducing agent in addition to its applications as an important energy carrier. The density function theory has been used to find the structural and optoelectronic properties of the Li$_{2}$NH compound. The exchange-correlation functional based GGA (generalized gradient approximation) is applied for calculating structural and optoelectronic properties. The expression for the formation is used to identify the stability, which is further confirmed by calculating the structural properties of Li$_{2}$NH. The calculations of the band structure show that a direct band gap is present between the occupied Li and N orbitals. A deep analysis of the optical properties was performed under incident photon radiation at energies up to 14 eV. Our calculated refractive index $n$(0) and the static part of the dielectric constant $\varepsilon_{2}$(0) are analogous to the experimental and other reported theoretical value.