Aalu Boda

Ground state properties of a two-electron system in a three-dimensional GaAs quantum dot with Gaussian confinement in a magnetic field

The ground state properties of a system of two interacting electrons trapped in a three-dimensional GaAs quantum dot with Gaussian confinement under the influence of an externally applied magnetic field (B) are obtained using a variational method with a Chandrashekhr-like wave function containing only three variational parameters and involving a modified Jastrow correlation factor. The phase diagram for the two-electron singlet bound state is obtained in the parameter space of the confinement potential. The pair density function is calculated as a function of the electron-electron separation for a couple of magnetic fields and its peak positions are obtained to study the behaviour of the size of the electron pair as a function of the confinement length and the depth of the potential. The size of the electron pair is also obtained directly by calculating the expectation value of the electron-electron separation with respect to the system wave function. Finally, the behaviour of the ground state energy is s...

Ground state energy of an exciton in a spherical quantum dot in the presence of an external magnetic field

The problem of an exciton trapped in a three dimensional Gaussian quantum dot is studied in the presence of an external magnetic field. A variational method is employed to obtain the ground state energy of the exciton as a function of the quantum dot size, the confinement strength and the magnetic field. It is also shown that the variation of the size of the exciton with the radius of the quantum dot.

Magnetic field effect on the energy levels of an exciton in a GaAs quantum dot: Application for excitonic lasers

The problem of an exciton trapped in a Gaussian quantum dot (QD) of GaAs is studied in both two and three dimensions in the presence of an external magnetic field using the Ritz variational method, the 1/N expansion method and the shifted 1/N expansion method. The ground state energy and the binding energy of the exciton are obtained as a function of the quantum dot size, confinement strength and the magnetic field and compared with those available in the literature. While the variational method gives the upper bound to the ground state energy, the 1/N expansion method gives the lower bound. The results obtained from the shifted 1/N expansion method are shown to match very well with those obtained from the exact diagonalization technique. The variation of the exciton size and the oscillator strength of the exciton are also studied as a function of the size of the quantum dot. The excited states of the exciton are computed using the shifted 1/N expansion method and it is suggested that a given number of stable excitonic bound states can be realized in a quantum dot by tuning the quantum dot parameters. This can open up the possibility of having quantum dot lasers using excitonic states.

The ground state magnetic moment and susceptibility of a two electron Gaussian quantum dot

The problem of two interacting electrons moving in a two-dimensional semiconductor quantum dot with Gaussian confinement under the influence of an external magnetic field is studied by using a method of numerical diagonalization of the Hamiltonian matrix with in the effective-mass approximation. The energy spectrum is calculated as a function of the magnetic field. We find the ground state magnetic moment and the magnetic susceptibility show zero temperature diamagnetic peaks due to exchange induced singlet-triplet oscillations. The position and the number of these peaks depend on the size of the quantum dot and also strength of the electro-electron interaction. The theory is applied to a GaAs quantum dot.The problem of two interacting electrons moving in a two-dimensional semiconductor quantum dot with Gaussian confinement under the influence of an external magnetic field is studied by using a method of numerical diagonalization of the Hamiltonian matrix with in the effective-mass approximation. The energy spectrum is calculated as a function of the magnetic field. We find the ground state magnetic moment and the magnetic susceptibility show zero temperature diamagnetic peaks due to exchange induced singlet-triplet oscillations. The position and the number of these peaks depend on the size of the quantum dot and also strength of the electro-electron interaction. The theory is applied to a GaAs quantum dot.

Spin persistent current of one electron quantum dot with Gaussian confinement

We have investigated the ground state persistent current of one-electron semiconductor quantum dot with a Gaussian confinement in the presence of an external magnetic field. The spin persistent current has been calculated by using a method of numerical diagonalization of the Hamiltonian matrix within the effective-mass approximation. It is shown that the persistent current almost increases with increasing the magnetic field for a particular value of the temperature. It is also shown that as a function of the quantum dot size, the diamagnetic current exhibits a maximum at a certain confinement length. It is furthermore shown that for a shallow potential, the persistent current shows an interesting maximum structure as a function of the depth of the potential.

Effect of Rasbha spin-orbit interaction on the ground state energy of a hydrogenic D0 complex in a Gaussian quantum dot

The ground state energy of a hydrogenic D0 complex trapped in a three-dimensional GaAs quantum dot with Gaussian confinement is calculated variationally incorporating the effect of Rashba spin-orbit interaction. The results are obtained as a function of the quantum dot size and the Rashba spin-orbit interaction. The results show that the Rashba interaction reduces the ground state energy of the system.

Energy spectrum of D0 centre in a spherical Gaussian quantum dot

The properties of a neutral hydrogenic donor (D0) centres have been studied for a GaAs semiconductor quantum dot with the Gaussian confinement potential. The energy levels of the ground state (n = 1) and the excited states of both the first excited (n = 2) and second excited (n = 3) configurations have been calculated by variational method. It has been shown that the excited states of the (D0) centre in quantum dot are bound for sufficiently strong confinement potential. The conditions of binding for the ground state as well as excited states have been determined as functions of the potential strength and quantum dot radius. The ground state electron energy is compared with those available in the literature.

Binding energy of an off - centre D0 complex in a GaAs quantum dot with Gaussian confinement

The binding energy of an off-centre neutral hydrogenic donor (D0) trapped in a three-dimensional quantum dot with Gaussian confinement is obtained by a variational method with a very simple wave function. The results are obtained as a function of the quantum dot size and the confinement strength and compared with those available in the literature. The binding energy is dependent on the dot size R, the impurity ion distance D and the confining potential depth V0.