I. Sökmen

Exact path-integral solution of the ring-shaped potential

Abstract The general new-time transformation method is used in obtaining the exact path-integral solution to the ring-shaped potential.

Geometrical effects on shallow donor impurities in quantum wires

Abstract We have studied theoretically the impurity binding energy for wires of different shapes (V-shaped quantum wire (V-QWR) and rectangular wire) with a variational procedure without using any coordinate transformation. The effective potential for V-QWR used in this work consists of a square well potential in the z-direction and full graded well potential in the x-direction. Our results are in good agreement with previous theoretical results, found by the coordinate transformation method. Furthermore, it is shown that the impurity binding energy in quantum wires is sensitive to the geometrical effects.

The effect of an intense laser field on magneto donors in semiconductors

Abstract The laser-field dependence of the binding energy of shallow-donor impurities in graded, and square quantum wells under the external magnetic field is calculated by a variational method and in the effective mass approximation. We have shown that, not only the ‘dressed’ potential, but also the shape of the confinement potential, the strength of the external magnetic field parallel to the growth direction, and the impurity position play very important roles in the determining the binding energy of a hydrogenic impurity.

The electric field effects on intersubband optical absorption of Si δ-doped GaAs layer

The intersubband transitions in Si δ-doped GaAs structures is theoretically investigated for different applied electric fields. For an uniform distribution the electronic structure has been calculated by solving the Schrodinger and Poisson equations self-consistently. From our calculations, it is found that the subband energies and intersubband optical absorption is quite sensitive to the applied electric field. This gives a new degree of freedom in various device applications based on the intersubband transitions of electrons.

Exciton absorption in quantum-well wires under the electric field

The binding energy of excitons, and interband optical absorption in quantum-well wires of GaAs surrounded by Ga1−xAlxAs is calculated in effective-mass approximation, using a variational approach. Results obtained show that the exciton binding energies, and optical absorption depend on the sizes of the wire and strength of the electric field. The additional confinement of particles in quantum well wire offers greater variety of electric field dependence in comparison to bulk materials and quantum well structures.

Binding energies of shallow donor impurities in different shaped quantum wells under an applied electric field

Abstract We present a variational method to compute the binding energies for a hydrogenic impurity located at the center of the finite parabolic (PQW), V-shaped (VQW or full graded well) and square (SQW) GaAs–Ga 1− x Al x As quantum wells under the electric field. The dependence of the ground state impurity binding energy on the applied electric field, the geometric shape of the quantum wells and well width is discussed together with the polarization effect.

Exact path integral solution of a class of potentials related to the rigid rotator

Abstract The path integral for the Scarf, Poschl-Teller, and Rosen-Morse potential problems are exactly calculated by connecting them to the rigid rotator problem through suitably chosen point canonical transformations.

Intersubband transitions for single, double and triple Si δ-doped GaAs layers

The intersubband transitions in single, double and triple Si δ-doped GaAs structures are theoretically studied for different applied electric fields. Electronic properties such as the confining potential, the subband energies and the eigen envelope wave functions have been calculated by solving the Schrodinger and Poisson equations self-consistently. We have seen that the intersubband transitions are very sensitive to the type of structure and are dependent on the applied electric field. The electric field and structure dependence of the intersubband optical absorption is interesting for potential device applications in a class of photodetectors and optical modulators.

Exact path-integral solution for a charged particle in a coulomb plus Aharonov-Bohm potential

Abstract We have calculated the path integral for a charged particle in a Coulomb plus Aharonov-Bohm potential by connecting it to Morse potential and Scarf potential problems. The energy eigenvalues are obtained from the poles of G ( E ) in the complex energy plane.

Si δ-doped GaAs structure with different dopant distribution models

We have theoretically investigated the diffusion of donor impurities of single Si δ-doped GaAs inserted into a quantum well at T=0 K. The spread of the impurities is taken into account in three different models: (i) a uniform distribution, (ii) a triangular distribution and (iii) a nonuniform distribution. In this article, the nonuniform distribution is different from the Gaussian distribution used by other authors. The electronic structures were calculated by solving the Schrodinger and Poisson equations self-consistently. We also found the confining potential, the charge density, the subband energies, the subband occupations and the Fermi energy. In this study, we have seen that the electronic structures are quite sensitive to the type of donor distribution when the thickness of the donor distribution (Δz) is large.