Yazar "Atav, Ulfet" seçeneğine göre listele

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    A detailed investigation of electronic and intersubband optical properties of AlxGa(1-x)As/Al0.3Ga0.7As/AlyGa1-yAs/Al0.3Ga0.7As multi-shell quantum dots
    (IOP PUBLISHING LTD, 2014) Kavruk, Ahmet Emre; Sahin, Mehmet; Atav, Ulfet
    In this study, we have investigated the electronic and intersubband optical properties of Al x Ga1-x As/Al0.3Ga0.7As/Al y Ga1-y As/Al0.3Ga0.7As multi-shell quantum dot heterostructures as a function of the Al doping concentrations in both the core (x) and the well (y) regions for cases with and without a hydrogenic donor impurity. Our results reveal how resonant absorption wavelengths and absorption coefficient strengths are changed by variation of the Al content in the core (x) and well (y) regions. Besides this, how the electronic and intersubband optical properties of this structure are affected by the existence of the impurity has also been shown. The physical reasons for this relationship between the electronic and optical properties of this structure and the Al content in the core and well regions have been discussed in detail.
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    Extraction of voltage-dependent series resistance from I-V characteristics of Schottky diodes
    (AMER INST PHYSICS, 2011) Durmus, Haziret; Atav, Ulfet
    A method for extracting the bias dependent behaviour of the series resistance of a Schottky barrier diode from experimental I-V data is presented. It was assumed that the behaviour of the Schottky barrier is well defined by thermionic emission theory. Relative merit of the method was determined by applying the method on some artificial sets of I-V data corresponding to known values of series resistances and comparing the results with existing methods. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3633116]
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    An investigation of the gate dependence in an electronic Aharonov-Bohm interferometer
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2012) Ozturk, Teoman; Kavruk, Ahmet Emre; Atav, Ulfet
    In this study we have obtained the dependence of the electronic distribution on the gate shape and the applied gate voltage in a quantum Hall effect based Aharonov-Bohm interferometer using a method presented in our previous studies. We have discussed the relation between the distribution of incompressible strips and observation of Aharonov-Bohm oscillations. We have obtained the distributions of the incompressible strips for various gate voltages and have shown that a gate potential sweep and a magnetic field sweep would be equivalent. Our calculations also predict that for wider gate separations it is possible observe a silent region while sweeping the magnetic field or the gate voltage. (C) 2012 Elsevier Ltd. All rights reserved.
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    Second harmonic generation in an asymmetric rectangular quantum well under hydrostatic pressure
    (ELSEVIER SCIENCE BV, 2007) Karabulut, Ibrahim; Atav, Ulfet; Safak, Haluk; Tomak, Mehmet
    The effects of structure parameters and hydrostatic pressure oil the electronic states and the second harmonic generation (SHG) susceptibility of asymmetric rectangular quantum Well (ARQW) are studied. The asymmetry of the potential can be controlled by changing the structural parameters and this adjustable asymmetry is important for optimizing the SHG susceptibility. We have calculated analytically the electronic states in ARQW within the framework of the envelope function approach. Numerical results for Al-x/Ga1-x/As/GaAs/AlxrGa1-xr. As quantum well are presented. The results obtained show that the hydrostatic pressure and the structure parameters of ARQW significantly influence the SHG susceptibility. This behavior in the SHG susceptibility gives a new degree of freedom in regions of interest for device applications. (c) 2007 Elsevier B.V. All rights reserved.
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    Thermodynamics of a two-dimensional interacting Bose gas trapped in a quartic potential
    (ELSEVIER SCIENCE BV, 2011) Karabulut, Elife O.; Koyuncu, Mustafa; Atav, Ulfet; Tomak, Mehmet
    We have studied the Bose-Einstein condensation (BEC) of an interacting Bose gas confined in a two-dimensional (2D) quartic potential by using a mean-field, semiclassical two-fluid model. A thermodynamic analysis including the chemical potential, condensate fraction, total energy, and specific heat has been carried out by considering different values of the interaction strength. Finally, we have found that the behaviour of the condensate fraction and specific heat of quartically trapped bosons differs from those of bosons trapped in a harmonic potential. (C) 2010 Elsevier B.V. All rights reserved.