Ahmet Emre Kavruk

Linear and nonlinear optical properties of GaAs/AlxGa1−xAs/GaAs/AlyGa1−yAs multi-shell spherical quantum dot

In this work, the optical properties of GaAs/AlxGa1−xAs/GaAs/AlyGa1−yAs multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed.

A detailed investigation of electronic and intersubband optical properties of AlxGa1−xAs/Al0.3Ga0.7As/AlyGa1−yAs/Al0.3Ga0.7As multi-shell quantum dots

In this study, we have investigated the electronic and intersubband optical properties of AlxGa1−xAs/Al0.3Ga0.7As/AlyGa1−yAs/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.

Edge state distribution in an Aharonov-Bohm electron interferometer in the integer quantum Hall regime

In this study we analyze the density distributions of the two dimensional electron system for an experimental geometry which is topologically equivalent of an Aharonov-Bohm interferometer in three dimensions in the quantum Hall regime and obtain the spatial distribution of the edge states. We employ the Thomas-Fermi approximation in our analysis and solve the Poisson equation in three dimensional using a multi grid technique. Also we obtain the distribution of incompressible strips for a wide range of magnetic fields strengths and comment on their relation with experimental results in literature.

The self-consistent calculation of the edge states at quantum Hall effect (QHE) based Mach-Zehnder interferometers (MZI)

Abstract The spatial distribution of the incompressible edge states (IES) is obtained for a geometry which is topologically equivalent to an electronic Mach–Zehnder interferometer, taking into account the electron–electron interactions within a Hartree type self-consistent model. The magnetic field dependence of these IES is investigated and it is found that an interference pattern may be observed if two IES merge or come very close, near the quantum point contacts. Our calculations demonstrate that, being in a quantized Hall plateau does not guarantee observing the interference behavior.

A detailed investigation of electronic and optical properties of single exciton in GaAs/AlxGa1-xAs/GaAs/AlyGa1-yAs multi-shell quantum dot

ABSTRACT The fundamental quantum mechanical properties of quantum dots (QDs), such as energy levels and corresponding wave functions, have important effects on characteristics of hi-tech electro-optical nano devices. The quantum mechanical properties of QDs are determined via the material content, shape and size of the structures. In this study, the electronic and interband optical properties of multi-shell quantum dot (MSQD) heterostructures as a function of the Al concentrations both in the interior and in the exterior barrier regions have been investigated theoretically for different sizes of core, barrier and well regions. For this purpose, Poisson and Schrödinger equations have been solved numerically by a self-consistent approach. Results of our calculations show that the electronic and optical properties of MSQDs can be changed effectively and this controllability makes them excellent candidates for new generation devices.