Donor Impurities In Quantum Wells Research Articles

Self‐Polarization of Hydrogenic Impurity in Quantum Wells Made of Different Materials

The effect of the external electric field on the ground state binding energy and self‐polarization of a hydrogenic donor impurity in quantum wells (QWs) made of different materials is calculated within the effective mass approximation using a variational scheme. The variations of binding energy and self‐polarization depending on well width, electric field, and impurity position have been studied in detail. For each QW made of different materials, it has been observed that the binding energy decreases with the increase of the electric field, whereas the self‐polarization increases. Also, it has been observed that InP/In1−x Ga x P has higher binding energy values among the structures discussed. It is seen that material selection has a noticeable effect on self‐polarization and binding energy in QW‐based structures.

Photoionization of donor impurities in quantum wells in an electric field

Recently, several authors have investigated the photoionization of impurities in quantum well systems. The shape of the cross-section profile depends upon the type of polarization of the incident radiation. There has not been sufficient work either on magnetic superlattices or on the effects of electric field on photoionization cross-section. In the present work, cross-sections are calculated for the GaAs/Al x Ga 1− x As quantum well system in external electric fields with finite and infinite barriers. Results are compared with available data in the literature.

The Effect of Uniaxial Stress on the Density of States of Shallow Donor Impurities in GaAs Quantum Wells

We have calculated the density of impurity states (DOIS) as a function of applied uniaxial stress of shallow hydrogen donor impurity in a quantum well (QW). The calculations were carried out using a variational procedure within the effective mass approximation. The results show that the density of impurity states is a function of applied stress. It is therefore important to take into consideration the effect of applied stress in a QW when carrying out experimental studies of optical and electronic properties of such heterostructures.

Polaron effects on the binding energy of a double donor impurity in quantum wells in an electric field

The binding energy of the single and double bound polaron bound to a helium-type donor impurity in quantum wells (QWs) subject to a perpendicular electric field are calculated by a variational method. The couplings of an electron and the impurity with various phonon modes are considered. The results show that the cumulative effects of the electron–phonon coupling and the impurity–phonon coupling can contribute appreciably to the binding energy for the single bound polaron but only in some severe conditions for the double bound polaron. They also show that the binding energy is sensitive to the electric field strength. The comparison between the binding energies in the case of the impurity placed at the quantum well center and at the quantum well edge is also given.

Polaronic effects on the energy levels of a double donor impurity in quantum wells in the presence of a magnetic field

In the presence of a magnetic field the Hamiltonian of the single or double polaron bound to a helium-type donor impurity in semiconductor quantum wells (QWs) are given in the case of positively charged donor center and neutral donor center. The couplings of an electron and the impurity with various phonon modes are considered. The binding energy of the single and double bound polaron in AlxlGa 1-xlAs/GaAs/AlxrGa 1-xrAs QWs are calculated. The results show that for a thin well the cumulative effects of the electron-phonon coupling and the impurity-phonon coupling can contribute appreciably to the binding energy in the case of ionized donor. In the case of neutral donor the contribution of polaronic effects are not very important, however the magnetic field significantly modifies the binding energy of the double donor. The comparison between the binding energies in the case of the impurity placed at the quantum well center and at the quantum well edge is also given.