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Arabshahi H.,Payame Nour University of Fariman | Arabshahi H.,Ferdowsi University of Mashhad
International Journal of Physical Sciences | Year: 2011

The transport of minority electrons up to 600 K temperature in silicon and germanium have been investigated, using an iterative approach. Theoretical expressions for electron scattering which take into account the ellipsoidal nature of the conduction band valleys have been incorporated into the model. Minority electron mobility calculations compared favorably with experimental results. The low temperature value of electron mobilty increases significantly with increasing doping concentration. The amount of neutron energy deposition in Si and Ge crystal of different sizes and at different distances from a neutron source has also been evaluated by using MCNP code. Then, the rate of atoms displacement in the crystals has been calculated using NRT Model. The damage to crystal is proportional to the energy deposition of neutron directly. Results show that the number of atoms displacement in the crystal is related to the neutron radiation damage and increased by enlarging of crystal size.© 2011 Academic Journals. Source


Arabshahi H.,Ferdowsi University of Mashhad | Sarlak F.,Payame Nour University of Fariman
Research Journal of Applied Sciences | Year: 2011

We introduce a new calculation method to compute the electron transport properties in semiconductor devices. Using the relaxation-time approximation, the Boltzmann transport equation for electrons has been solved to calculate the thermal energy flux, electrical conductivity, seebeck coefficient and thermal conductivity. © 2011 Medwell Journals. Source


Rahnamaye Aliabad H.A.,Kharazmi University | Mahmoodi N.,Azad University of Mashhad | Arabshahi H.,Ferdowsi University of Mashhad | Arabshahi H.,Payame Nour University of Fariman
International Journal of Physical Sciences | Year: 2011

We have studied the structural, electronical and optical properties of pure α-Al2O3 (corundum) and doped with manganese by the first principles calculations method based on the density functional theory (DFT), with generalized gradient approximation (GGA). Obtained results show that α-Al2O3 has an energy gap of 6.3 eV and the substitution of manganese decreases the energy gap so that spin splitting effect is observed. Calculated optical results show that with adding this impurity, reflectivity increase at low energy and decreases at high energy; also static refractive index increases. ©2011 Academic Journals. Source


Arabshahi H.,Payame Nour University of Fariman | Arabshahi H.,Ferdowsi University of Mashhad
International Journal of Physical Sciences | Year: 2011

A new calculation method has been developed and used to model electron transport properties in semiconductor devices under thermal and electrical applications. Using the relaxation-time approximation, the Boltzmann transport equation is solved using the currently established values of the material parameters. This method is used to carry out the thermal energy flux, electrical conductivity, seebeck coefficient and thermal conductivity. Using the driven equations, thermal and electrical properties in CdTe and CdSe materials were been calculated. The calculated results are in fair agreement with other recent calculations obtained by experimental methods. © 2011 Academic Journals. Source


Arabshahi H.,Payame Nour University of Fariman
Romanian Reports in Physics | Year: 2011

In this research we have solved the rate equations for GaAs/AlGaAs self-assembled quantum dot laser with considering the homogeneous and inhomogeneous broadening of the optical gain using fourth order Runge-Kutta method. With increasing the full width at half maximum (FWHM) of homogeneous broadening, the threshold current, turn-on delay and steady-state photons increase because of increasing the density of states in the central group. Our calculation results show also that the simulated self-assembled dot laser reaches the steady-state faster and the lasing emission is not single mode due to the gain saturation. Source

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