Hassan Safari - Academia.edu (original) (raw)
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Papers by Hassan Safari
In this paper , to investigate the effect of AlGaN electron blocking layer (EBL) on the character... more In this paper , to investigate the effect of AlGaN electron blocking layer (EBL) on the character istics of InGaN/GaN multi-quantum-well solar cells, at first this structure without EBL layer was simulated using Silvacoatlas software and efficiency of 27.80% was achieved. Then by inser ting a 20nm p-Al0.1Ga0.9N electron blocking layer the cell character istics was evaluated for different doping values, and the optimal efficiency for 2×10 cm doping concentration was obtained 40.05%. Simulation results show that inserting the p-AlGaN EBL layer to the cell structure increased the conduction band offset. This will block the flow of electrons to the p-region, consequently the solar cell efficiency will be increased due to the reducing of recombination and improving the hole collection.
Optics Communications, 2002
The three dimensional scheme of the Green function approach of the electromagnetic field quantiza... more The three dimensional scheme of the Green function approach of the electromagnetic field quantization is extended to the background medium made up of two adjacent semi-infinite dielectrics which show both loss and dispersion. It is shown that this system separates into a singlet system providing the normal polarization state of the electric field and a doublet system giving both the parallel state of polarization and the longitudinal part of the field. The longitudinal field expression is also derived by using the usual approach of vector decomposition. The overall results enable us to present the form of the field operators for each state of polarization as well as the longitudinal field contribution. The equal-time canonical commutation relations between the vector potential operator and its conjugate generalized momentum are verified in each case.
Physical Review A, 2008
We study single-and two-atom van der Waals interactions of ground-state atoms which are both pola... more We study single-and two-atom van der Waals interactions of ground-state atoms which are both polarizable and paramagnetizable in the presence of magnetoelectric bodies within the framework of macroscopic quantum electrodynamics. Starting from an interaction Hamiltonian that includes particle spins, we use leading-order perturbation theory to express the van der Waals potentials in terms of the polarizability and magnetizability of the atom(s). To allow for atoms embedded in media, we also include local-field corrections via the real-cavity model. The general theory is applied to the potential of a single atom near a half space and that of two atoms embedded in a bulk medium or placed near a sphere, respectively.
In this paper , to investigate the effect of AlGaN electron blocking layer (EBL) on the character... more In this paper , to investigate the effect of AlGaN electron blocking layer (EBL) on the character istics of InGaN/GaN multi-quantum-well solar cells, at first this structure without EBL layer was simulated using Silvacoatlas software and efficiency of 27.80% was achieved. Then by inser ting a 20nm p-Al0.1Ga0.9N electron blocking layer the cell character istics was evaluated for different doping values, and the optimal efficiency for 2×10 cm doping concentration was obtained 40.05%. Simulation results show that inserting the p-AlGaN EBL layer to the cell structure increased the conduction band offset. This will block the flow of electrons to the p-region, consequently the solar cell efficiency will be increased due to the reducing of recombination and improving the hole collection.
Optics Communications, 2002
The three dimensional scheme of the Green function approach of the electromagnetic field quantiza... more The three dimensional scheme of the Green function approach of the electromagnetic field quantization is extended to the background medium made up of two adjacent semi-infinite dielectrics which show both loss and dispersion. It is shown that this system separates into a singlet system providing the normal polarization state of the electric field and a doublet system giving both the parallel state of polarization and the longitudinal part of the field. The longitudinal field expression is also derived by using the usual approach of vector decomposition. The overall results enable us to present the form of the field operators for each state of polarization as well as the longitudinal field contribution. The equal-time canonical commutation relations between the vector potential operator and its conjugate generalized momentum are verified in each case.
Physical Review A, 2008
We study single-and two-atom van der Waals interactions of ground-state atoms which are both pola... more We study single-and two-atom van der Waals interactions of ground-state atoms which are both polarizable and paramagnetizable in the presence of magnetoelectric bodies within the framework of macroscopic quantum electrodynamics. Starting from an interaction Hamiltonian that includes particle spins, we use leading-order perturbation theory to express the van der Waals potentials in terms of the polarizability and magnetizability of the atom(s). To allow for atoms embedded in media, we also include local-field corrections via the real-cavity model. The general theory is applied to the potential of a single atom near a half space and that of two atoms embedded in a bulk medium or placed near a sphere, respectively.