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Öğe Binding energy and self-polarization as function of energy density in GaAs/AlAs quantum well wires(Elsevier Science Bv, 2006) Erdogan, I.; Akankan, O.; Akbas, H.In this work, we have investigated the effect of both external electric and magnetic fields on the ground-state binding energy and the self-polarization of hydrogenic impurity in square and cylindrical GaAs/AlAs quantum well wires as function of energy density and impurity position. The binding energies and self-polarizations were obtained using the effective-mass approximation within a variational scheme. (c) 2006 Elsevier B.V. All rights reserved.Öğe Binding energy of 2p-bound state of a hydrogenic donor impurity in a GaAs/Ga1-xAlxAs spherical quantum dot under hydrostatic pressure(Elsevier, 2014) Bulut, P.; Erdogan, I.; Akbas, H.By using a variational procedure within the effective mass approximation, we calculated the 2p state binding energy, E-2pha(x,P), and the binding energy turning point, R-2pEbT (X, P) of a hydrogenic donor impurity located at the centre of the GaAs GaAs/Ga1-xAlxAs spherical quantum dot under the influence of hydrostatic pressure. The results obtained show that the binding energy turning point, R-2pEbT(X, P) is an important factor in dealing with the 2p bound state of a hydrogenic donor impurity embedded at the centre of the quantum dot. (C) 2014 Elsevier By. All rights reserved,Öğe The diamagnetic susceptibility of hydrogenic donor in two-dimensional semiconductors with anisotropic effective mass of carriers(Academic Press Ltd- Elsevier Science Ltd, 2012) Akbas, H.; Bulut, P.; Dane, C.; Skarlatos, Y.In this study, the effects of quantum confinement and effective mass anisotropy parameter on the diamagnetic susceptibility of a hydrogenic donor placed in GaAs. Si, and Ge quantum wells with infinite confinement potential are investigated in the effective mass and parabolic band approximations by using two and one parameter trial wave functions. It is observed that the diamagnetic susceptibility of a hydrogenic donor in anisotropic quantum wells is essentially equal to the transverse diamagnetic susceptibility part when well widths are larger than L > 100 angstrom, and the impurity is located at center. Moreover, a two parameter trial wave function model gives higher values of diamagnetic susceptibility, except for chi(z) (GaAs). (C) 2011 Elsevier Ltd. All rights reserved.Öğe The effect of dielectric constant on binding energy and impurity self-polarization in a GaAs-Ga1-xAlxAs spherical quantum dot(Indian Assoc Cultivation Science, 2017) Mese, A. I.; Cicek, E.; Erdogan, I.; Akankan, O.; Akbas, H.The ground state, 1s, and the excited state, 2p, energies of a hydrogenic impurity in a GaAs-Ga1-xAlxAs spherical quantum dot, are computed as a function of the donor positions. We study how the impurity self-polarization depends on the location of the impurity and the dielectric constant. The excited state anomalous impurity self-polarization in the quantum dot is found to be present in the absence of any external influence and strongly depends on the impurity position and the radius of the dot. Therefore, the excited state anomalous impurity self-polarization can give information about the impurity position in the system. Also, the variation of E-b1s and E-b2p with the dielectric constant can be utilized as a tool for finding out the correct dielectric constant of the dot material by measuring the 1s or 2p state binding energy for a fixed dot radius and a fixed impurity position.Öğe The effect of magnetic field in a GaAs/AlAs spherical quantum dot with a hydrogenic impurity(Elsevier, 2009) Akbas, H.; Dane, C.; Guleroglu, A.; Minez, S.Using a variational procedure within the effective-mass approximation we calculate the binding and normalized binding energies of a hydrogenic donor impurity in a GaAs/AlAs spherical quantum dot, under the action of homogeneous magnetic field (B) over right arrow (0, 0, B) directed along the z-axis. A proper choice of the dot radius and the magnetic field can largely change the normalized binding energy NEbB of a central hydrogenic impurity in the spherical quantum dot, which may be used to feel the small change in the dot radius. (C) 2008 Elsevier B.V. All rights reserved.Öğe Effect of spatial electric field on the sub-band energy in a cubic GaAs/AlAs quantum dot(Elsevier Science Bv, 2007) Dane, C.; Akbas, H.; Talip, N.; Kasapoglu, K.The electron sub-band energy of a cubic GaAs/AlAs quantum dot under an applied spatial electric field is theoretically investigated within a variational scheme. In this case, we show that the electron sub-band energy E decreases with spatial electric field strength F and increases or decreases depending upon the orientation of the spatial electric field. (C) 2007 Elsevier B.V. All rights reserved.Öğe Effects of Electrolytes on Interfacial and Micelle Properties of C.I. Reactive Orange 16 - Dodecylpyridinium Chloride Binary System(Carl Hanser Verlag, 2011) Akbas, H.; Aydemir, M.The effect of electrolytes on the interaction between the anionic dye C.I. Reactive Orange 16 and the cationic surfactant dodecylpyridinium chloride was investigated using surface tension measurement in a certain concentration range. The influence of the concentration of electrolyte on critical micelle concentration (CMC) values was observed in the following order; 0.1 M NaCl > 0.5 M NaCl > 1.0 M NaCl. Also, the influence of the electrolyte cations was observed as Na+ > Mg2+ > K+. An increase on CMC values of dye-surfactant solution with increasing electrolyte concentration is explained as charge screening and also the decrease in these values for higher concentration of electrolyte is attributed to the change of micelle shape. Furthermore this change is due to ionic polarizability, valency and hydrated radius. Using Rubingh's regular solution theory, the values of micellar interaction parameters (beta), were found as negative in all studied mixtures.Öğe The effects of geometrical shape and impurity position on the self-polarization of a donor impurity in an infinite GaAs/AlAs tetragonal quantum dot(Indian Assoc Cultivation Science, 2021) Akankan, O.; Erdogan, I.; Mese, A. I.; Cicek, E.; Akbas, H.Using the variational method within the effective-mass approximation, the effects of geometrical shape and impurity position on the ground-state self-polarization and binding energy of a donor impurity are theoretically studied for the infinite GaAs/AlAs tetragonal quantum dot. We have found that the ground-state self-polarization and binding energy depend on geometrical shape and impurity-AlAs layer distance.Öğe Effects of hydrostatic pressure on the self-polarization in GaAs/Ga1-x Alx As quantum wells under the electric field(Elsevier Science Bv, 2009) Erdogan, I.; Akankan, O.; Akbas, H.In this work we have calculated the hydrostatic pressure and the electric field effect on the self-polarization (SP) in GaAs/Ga1-xAlx As quantum well, The binding energies of donors and the self-polarization in quantum wells are investigated with a variational method considering the influence of finite barriers under hydrostatic pressure. In calculations, we take into account the electronic effective mass, dielectric constant, barrier height, well size, varying with pressure. We find that the effect of hydrostatic pressure on the self-polarization depends on value of the well widths and applied electric fields. (C) 2009 Elsevier B.V. All rights reserved.Öğe Electric field effect in a GaAs/AlAs spherical quantum dot(Elsevier Science Bv, 2008) Dane, C.; Akbas, H.; Minez, S.; Guleroglu, A.Using a variational procedure within the effective-mass approximation we calculate the binding and normalized binding energy (NEbF) of a shallow donor impurity in a GaAs/AlAs spherical quintum dot, under the action of constant uniform electric field applied in the z-direction. A proper choice of the dot radius and electric field call largely change NEbF of a centre shallow impurity in the spherical quantum dot, which may be used to feel the small change in the dot radius. (C) 2008 Elsevier B.V. All rights reserved.Öğe Ground state normalized binding energy of impurity in asymmetric quantum wells under hydrostatic pressure(Academic Press Ltd- Elsevier Science Ltd, 2016) Akbas, H.; Sucu, S.; Minez, S.; Dane, C.; Akankan, O.; Erdogan, I.We have studied and computed variationally the impurity energy, impurity energy turning points, and ground state normalized binding energy as functions of the impurity position for shallow impurity in asymmetric quantum wells under hydrostatic pressure. We found that the normalized binding energy significantly depends on the asymmetry of the well, besides depending on,the impurity position and hydrostatic pressure. Also, the dependence of the positive normalized binding energy on the pressure can be used to find out the degree of the asymmetry of the well or the impurity position in the well. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Hydrogenic donor in asymmetric AlxLGa1-xLAs/GaAs/AlxRGa1-xRAs quantum wells(Elsevier Science Bv, 2014) Akbas, H.; Dane, C.; Erdogan, I.; Akankan, O.In this work we study the effects of barrier height ratio V-L/V-R on asymmetric AlxLGa1-xLAs/GaAs/AlxRGa1-xRAs quantum wells in absence of external influences. We use a variational method within the effective mass approximation to observe the effects of the barrier height ratio. It has been observed that the binding energy of the impurity, the expectation value of the electron-impurity distance along the z-direction, density of impurity states, and edge binding energy difference depend strongly on the barrier height ratio. Furthermore we present new curves that analyze the binding energy of asymmetric quantum wells as functions of barrier height ratio. (C) 2014 Elsevier B.V. All rights reserved.Öğe The hydrostatic pressure and electric field effects on the normalized binding energy of hydrogenic impurity in a GaAs/AlAs spherical quantum dot(Elsevier Science Bv, 2011) Dane, C.; Akbas, H.; Guleroglu, A.; Minez, S.; Kasapoglu, K.A theoretical study of combined effects of the hydrostatic pressure and the electric field on the subband ground state energy and on the normalized ground state binding energy of a hydrogenic donor impurity on center located in a GaAs/AlAs spherical quantum dot with fixed dot radius is presented. The study is performed in the framework of the effective mass and parabolic band approximations and using a variational procedure. As a key result, it may be possible to gather high resolution maps of electric field on the studied structure with described technique. (C) 2011 Elsevier B.V. All rights reserved.Öğe Hydrostatic pressure effects on impurity states in GaAs/AlAs quantum wells(Academic Press Ltd- Elsevier Science Ltd, 2011) Akbas, H.; Erdogan, I.; Akankan, O.Within the framework of effective-mass approximation, we have studied the effects of hydrostatic pressure on the binding energy of a shallow donor impurity in an infinite quantum well by means of a variational method. It is found that the first derivative of the binding energy and energy shift is reliable parameter for describing the structure. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Simultaneous effects of electric and magnetic fields in a GaAs/AlAs spherical quantum dot with a hydrogenic impurity(Elsevier, 2010) Dane, C.; Akbas, H.; Minez, S.; Guleroglu, A.In this paper, the effects of electric and magnetic fields on the ground state of a hydrogenic on-centre donor in a GaAs/AlAs spherical quantum dot have been studied. A variational approach within the framework of effective mass approximation is used in the calculations. Overall, the analysis shows that a proper choice of the dot radius and the electric and magnetic fields can largely change the normalized binding energy, which in turn may be used to feel the small change in dot radius and thus detect different magnetic field strengths. (C) 2010 Elsevier B.V. All rights reserved.Öğe Simultaneous effects of temperature, hydrostatic pressure and electric field on the self-polarization and electric field polarization in a GaAs/Ga0.7Al0.3As spherical quantum dot with a donor impurity(Academic Press Ltd- Elsevier Science Ltd, 2013) Erdogan, I.; Akankan, O.; Akbas, H.Based on the effective mass approximation within a variational approach, we have calculated the temperature effect on the donor binding energy, self-polarization (SP), and electric field polarization (FP) in a GaAs/Ga0.7Al0.3As spherical quantum dot (SQD) with off center donor impurity under the action of electric field and hydrostatic pressure. The binding energy and polarizations are computed as a function of the temperature, and electric field strength for two different pressures. The results show that the values of the self-polarization are greater than the values of the electric field polarization. There are no reports on comparison of the SP and FP in low-dimensional structures, so far. (C) 2013 Published by Elsevier Ltd.Öğe The size effect of the tetragonal quantum dot on the self-polarization under the spatial electric field(Indian Assoc Cultivation Science, 2024) Cicek, E.; Mese, A. I.; Akankan, O.; Akbas, H.In this paper, the effect of the spatial electric field on the hydrogenic impurity self-polarization and binding energy in a GaAs/AlAs tetragonal quantum dot are calculated by the variational method based on the effective mass approximation. We have shown that the self-polarization and binding energy of a hydrogenic impurity in a tetragonal quantum dot depends strongly on the theta angle of the spatial electric field, the size effect (L-z/L ratio (M)), the volume of the dot, and impurity position. Furthermore, we define the angle theta(max), which aligns the spatial electric field vector with the position vector of the hydrogenic impurity on the diagonal axis. It has been noted that self-polarization reaches its peak at this particular angle.Öğe Spatial electric and. axial magnetic fields effect in GaAs-AlAs quantum wires(Elsevier, 2007) Akankan, O.; Okan, S. E.; Akbas, H.In this work. we investigated the effect of both spatial electric and axial magnetic fields on the impurity ground state energy and the polarization of a donor impurity in square GaAs/AlAs QWWs. We show that the impurity ground state energy and the polarization depends strongly not only on the width of QWW, but also on the applied spatial component of the electric field and the impurity position. (c) 2006 Elsevier B.V. All rights reserved.Öğe Spatial electric field effect in a GaAs/AlAs tetragonal quantum dot(Elsevier Science Bv, 2008) Akbas, H.; Dane, C.; Kasapoglu, K.; Talip, N.Within the effective-mass approximation and with two-parameter variational procedure we have calculated the effect of spatial electric field and ratios of dot edge lengths(c/a) on the electron sub-band energy and the polarization of an electron in the tetragonal GaAs/AlAs quantum dot. It is found that the electric flux Phi leaving the tetragonal dot is reliable parameter for describing the structure. (C) 2007 Elsevier B.V. All rights reserved.Öğe Spatial electric field effect on the self-polarization in GaAs/AlAs square quantum-well wires(Elsevier Science Bv, 2006) Akankan, O.; Erdogan, I.; Akbas, H.In the presence of a spatial electric field the ground-state energy and self-polarization (SPE) of hydrogenic impurity in infinite square quantum-well wire is calculated, where the spatial electric field is applied parallel to the position vector of the impurity. It is found that impurity ground-state energy and SPE depend strongly on the axial component of the spatial electric field and on the coordinates of the impurity position x(i),y(i), and z(i). (c) 2006 Elsevier B.V. All rights reserved.
