Semi-exponential Quantum Wells Research Articles

Magnetic field and anisotropic parabolic potential effects on ground state binding energy of impurity magnetopolaron in asymmetrical semi-exponential quantum wells

We performed the ground state binding energy (GSBE) and vibrational frequency (VF) of strong-coupling impurity magnetopolaron (SCIM) in asymmetrical semi-exponential quantum wells (ASEQWs) containing a hydrogen-like impurity in the center exposed to a uniform magnetic field through Lee-Low-Pines unitary transformation and linear combination operation method based on effective mass approximation. The results were expressed as functions of GSBE and VF for different magnetic field cyclotron frequency (MFCF) and Coulombic impurity potential (CIP) strength, the positive criteria of ASEQWs along the growth direction of QW and effectual confinement lengths of APCP along the coordinates were analyzed. Our findings revealed that the VF and GSBE were enhanced by increasing magnetic field cyclotron frequency and the parameter of asymmetrical semi-exponential confinement potential (ASECP), which was increased by reducing APCP effectual confinement length along the directions of coordinates. The above observations could be because of quantum size confinement effects.

The influences of hydrogen-like impurities and magnetic field on magnetopolaron in asymmetric semi-exponential and parabolic potential quantum wells

In the current research, the impacts of anisotropic parabolic confinement potential (APCP) on strong-coupled impurity bound magnetopolaron (SCIMP) in asymmetrical semi-exponential quantum wells (ASEQWs) containing hydrogen-like impurities (HLIs) at their center under uniform magnetic fields applied along the direction of z axis have been theoretically investigated. Lee-Low-Pine unitary transformation and linear combination operation methods were applied for the derivation of formulations for ground state energy (GSE) and the mean number of LO phonons (MNLOP) of SCIMPs. Also, GSE and MNLOP as functions of magnetic field cyclotron frequency, Coulombic impurity potential (CIP) strength, APCP effective confinement strengths along x and y directions, and two positive parameters of asymmetrical semi-exponential confinement potential (ASECP) were acquired. Numerical results were expressed for a typical CsI. It was found that when considering magnetic field, APCP, CIP, ASECP, GSE and MNLOP were increased.

Parabolic Potential Effect on Binding Energy of Impurity Polaron in Asymmetrical Semi-Exponential Quantum Wells

Parabolic Potential Effect on Binding Energy of Impurity Polaron in Asymmetrical Semi-Exponential Quantum Wells

The Influences of a Magnetic Field and Anisotropic Parabolic Potential on the Vibrational Frequency of Polaron in Asymmetrical Semi-exponential Quantum Wells

The Influences of a Magnetic Field and Anisotropic Parabolic Potential on the Vibrational Frequency of Polaron in Asymmetrical Semi-exponential Quantum Wells

Ground State Binding Energy of the Strong-coupling Polaron in Asymmetrical Semi-exponential Quantum Wells

Ground State Binding Energy of the Strong-coupling Polaron in Asymmetrical Semi-exponential Quantum Wells

Temperature effect on the ground state energy and the longitudinal optical-phonon mean number of the impurity polaron in asymmetrical 2D RbCl semi-exponential quantum wells

Temperature effect on the ground state energy and the longitudinal optical-phonon mean number of the impurity polaron in asymmetrical 2D RbCl semi-exponential quantum wells

Nonlinear optical properties of a semi-exponential quantum wells: Effect of high-frequency intense laser field

In this present work, the effect of non-resonant, mono-chromatic intense laser field (ILF) on the linear and nonlinear optical properties of a semi-exponential quantum well (SEQW) is investigated theoretically within the effective-mass and envelope wave function approach. The bound subband energy levels and their envelope wave functions of the structure are calculated by using the diagonalization method. The optical properties of the system are obtained by using the compact-density matrix approach. The obtained numerical results show that the applied ILF and structure parameters have a significant impact on the optical properties of these structures, such as the linear, third-order nonlinear and total absorption coefficients and relative refractive index changes. Furthermore, from the findings of this study, it has been concluded that the linear and nonlinear optical properties in a SEQW under the ILF can be tuned by changing structure parameters, such as the effective range and depth of the system.

Temperature Effect on Vibration Frequency of the Strong-Coupling Polaron in RbCl Asymmetrical Semi-exponential Quantum Wells

We carried out the theoretical study of the influence of temperature on the polaron vibration frequency in the RbCl asymmetrical semi-exponential quantum wells by using the quantum statistical theory. The vibration frequency and the ground-state binding energy (GSBE) varying with the temperature and the Coulomb interaction are calculated by employing the Lee–Low–Pines transformation method combined with linear combination operation technique. We show that the vibration frequency and the GSBE will be enhanced with raising the temperature and the Coulomb repulsion interaction.

The Binding Energy of Impurities in the Asymmetrical Semi-Exponential Quantum Wells

Within the framework of effective-mass and envelope wave function approach, using a variational method, we have investigated the binding energy of shallow-donor impurities in an asymmetrical semi-exponential quantum wells (ASEQW). The obtained numerical results show that the structure parameters (σ and, V0) lead to significant changes in the impurity binding energy. Furthermore, these results show that the hydrogenic donor impurity binding energy may be increased or decreased as a function of the impurity position in quantum well.

Temperature and impurity effects on the vibrational frequency of the strongly-coupled polaron in asymmetrical semi-exponential RbCl quantum wells

Properties of the vibrational frequency (VF) and the ground state binding energy (GSBE) of the strong-coupled polaron in asymmetrical semi-exponential quantum wells (ASEQWs) with a hydrogen-like impurity (HLI) at the origin of coordinates are investigated. The temperature effects on the VF and the GSBE are taken into account by using the quantum statistics theory (QST). Based on the linear combination operation and LLP unitary transformation methods, the variations of the VF and the GSBE varying with the temperature and the strength of the Coulombic impurity potential (CIP) are discussed. We have found that the VF and the GSBE are increasing functions of the temperature and the CIP.

Polaron effects on the third-harmonic generation in asymmetrical semi-exponential quantum wells

The polaron effects on the third-harmonic generation (THG) are investigated theoretically for electrons confined in asymmetrical semi-exponential quantum wells (ASEQWs). The analytic expression for the THG in ASEQWs is derived by using the compact-density-matrix approach and the iterative method. The numerical results are presented for GaAs/AlGaAs ASEQWs. The results demonstrate that polaron effects have an important influence on the THG. It is found that the THG is obviously increased when considering the electron-LO-interaction.

Polaron effects on the second-harmonic generation in asymmetrical semiexponential quantum wells

Polaron effects on the second-harmonic generation (SHG) in asymmetrical semiexponential quantum wells (ASEQWs) are investigated theoretically. By using the framework of the compact-density-matrix approach and iterative method, the analytical expression of the SHG coefficients in ASEQWs is presented. Numerical results are illustrated for a typical GaAs/AlGaAs. By considering the electron--LO--phonon interaction (ELOPI), the energy levels and the wave functions of an electron confined in ASEQWs are obtained. It is found that whether we consider the ELOPI or not, the incident photon frequency $\omega$ and parameters $U_0$ and $\sigma$ also affect the SHG coefficient obviously.

Studies on the third-harmonic generation coefficients in asymmetrical semi-exponential quantum wells

Third-harmonic generation (THG) coefficients in asymmetrical semi-exponential quantum wells (ASEQW) are studied theoretically. We obtain the eigenfunctions and the energy eigenvalues by means of solving Schrödinger equation within the framework of effective mass approximation. Besides, the analytic expression of THG coefficients is acquired through using compact-density-matrix approach and iterative method. The results show that both the amount of peaks of THG coefficients and the magnitude of peaks are significantly affected by σ and U0, which are parameters refer to the intensity of confinement potential in the growth direction of ASEQW.

Second-harmonic generation coefficients in asymmetrical semi-exponential quantum wells

Second-harmonic generation (SHG) coefficients in asymmetrical semi-exponential quantum wells (ASEQW) are studied theoretically. The eigenfunctions and the energy eigenvalues are obtained by solving Schrödinger equation within the framework of effective mass approximation. In addition, the analytic expression of SHG coefficients is acquired by using compact-density-matrix approach and iterative method. The results show that both σ and U0, which are parameters of the bound potential in the growth direction of ASEQW, have great influences on the magnitude and the resonant frequencies of SHG coefficients.

Linear and nonlinear intersubband optical absorption and refractive index change in asymmetrical semi-exponential quantum wells

Linear and nonlinear intersubband optical absorption and refractive index change in asymmetrical semi-exponential quantum wells are theoretically investigated within the framework of the compact–density–matrix approach and iterative method. The wave functions are obtained by using the effective mass approximation. The energy levels are obtained by numerical method. It is found that the optical absorption coefficients and refractive index changes are strongly affected not only by σ and U0, but also by the incident optical intensity.