Gaussian Quantum Wells Research Articles

Bose–Einstein distribution temperature features of quasiparticles around magnetopolaron in Gaussian quantum wells of alkali halogen ions

Abstract We have applied strong coupling unitary transformation method combined with Bose–Einstein statistical law to investigate magnetopolaron energy level temperature effects in halogen ion crystal quantum wells. The obtained results showed that under magnetic field effect, magnetopolaron quasiparticle was formed through the interaction of electrons and surrounding phonons. At the same time, magnetopolaron was influenced by phonon temperature statistical law and important energy level shifts down and binding energy increases. This revealed that lattice temperature and magnetic field could easily affect magnetopolaron and the above results could play key roles in exploring thermoelectric conversion and conductivity of crystal materials.

Magnetic field modulation of polaron relaxation coherence effects in III-V semiconductor Gaussian quantum wells

We have theoretically investigated the effects of the cyclotron frequency of magnetic field, the initial depth and the range of the asymmetrical Gaussian confinement potential on the vibrational frequency, ground state energy, excited state energy and coherence time of polaron in III-V semiconductors by using a linear combination operator and unitary transformations methods. Through numerical calculations, we find some interesting phenomena that the polaron decreases the energy level and releases the energy of a phonon to jump. From the point of view of the energy level of the polaron, which is αℏωLO energy lower than that of the electron, and the transition of the polaron to the ground state will have a change in lattice position, and the lattice relaxation phenomenon will appear. The theoretical study of the quantum coherence effect of polaron energy levels will provide guidance for the development of optoelectronic devices and the transmission of quantum information.

The weak coupling decay magnetopolaron effect in an asymmetric Gaussian quantum well

The famous Lee–Low–Pines transformation method is employed to receive the ground-state energy (GSE), first excited state energy (FESE), excited energy (EE), transition frequency (TF), and ground state binding energy (GSBE) of the weak coupling magnetopolaron in the asymmetrical Gaussian potential quantum well (AGPQW) under the influence of decay magnetic field (DMF). Results demonstrate that the GSE, FESE, EE, and TF are increasing functions of the depth of the AGPQW and the initial magnetic induction intensity (IMII) and decreasing functions of the range of the AGPQW and the DMF's decay frequency (DF) and decay time (DT) using GaAs crystals for numerical simulations. In contrast, the GSBE can decrease with the depth of the AGPQW and the IMII and increase with the range of the AGPQW and the DF and DT. The obtained research results are theoretically significant for recognizing, understanding, and applying of magnetopolaron effect of GaAs crystals.

The Impurity and Decay-Magnetic Polaron Effects in III–V Compound Gaussian Quantum Wells

The effects of a decay magnetic field and hydrogen-like impurities on the ground-state binding energy (GSBE) and ground-state energy (GSE) of weak-coupling bound polarons in asymmetrical Gaussian potential (AGP) III–V compound quantum wells (QWs) were studied based on unitary transformation methods and linear combination operators. By numerical calculation, we found that the polarons were affected by the AGP, the decay magnetic field, Coulomb impurities, and the type of crystal, which led to a series of interesting phenomena, such as changes in the ground-state energy and the ground-state binding energy. The results obtained provide good theoretical guidance for optoelectronic devices and quantum information.

The influences of parabolic potential and magnetism on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells

In this research, the effects of magnetism and parabolic potential on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells (AGQWs) were investigated. To do so, the following six parameters were studied, temperature, AGQW barrier height, Gaussian confinement potential (GCP) width, confinement strengths along the directions of [Formula: see text] and [Formula: see text], as well as magnetic field cyclotron frequency. The relationships among frequency oscillation, AGQW parameters and polaron ground state energy in RbCl crystal were studied based on linear combination operator and Lee–Low–Pines unitary transformation. It was concluded that ground state energy absolute value was decreased by increasing GCP width and temperature, and increased with the increase of confinement strength along [Formula: see text] and [Formula: see text] directions, cyclotron frequency of magnetic field and barrier height of AGQW. It was also found that vibrational frequency was increased by enhancing confinement strengths along the directions of [Formula: see text] and [Formula: see text], magnetic field cyclotron frequencies, barrier height AGQW and temperature and decreased with the increase of GCP width.

The effect of parabolic potential on ground state energy and vibration frequency of magnetopolaron in asymmetric Gaussian potential quantum wells

Anisotropy parabolic potential (APP) effects on ground state (GS) energy [Formula: see text] and the vibration frequency (VF) [Formula: see text] of weak-coupled magnetopolaron (MP) in asymmetric Gaussian quantum wells (AGQWs) were investigated using the linear combination operator and unitary transformation method. The obtained results showed that [Formula: see text] and [Formula: see text] were increased by increasing the barrier height [Formula: see text] of AGQWs as well as transverse and longitudinal confined strengths [Formula: see text] and [Formula: see text] of APP and decreased with increase in the asymmetric Gaussian confinement potential (AGCP) range [Formula: see text] and transverse and longitudinal effective confined lengths [Formula: see text] and [Formula: see text] of APP. Thus, the GS energy and VF of MP could be changed by adjusting the confinement parameters of the APP and AGCP. The study of quantum wells’ semiconductor materials has broad potential applications in semiconductor lasers, optoelectronic devices and quantum information.

Numerical simulation of linear and nonlinear optical properties in heterostructure based on triple Gaussian quantum wells: effects of applied external fields and structural parameters

Numerical simulation of linear and nonlinear optical properties in heterostructure based on triple Gaussian quantum wells: effects of applied external fields and structural parameters

The effect of a parabolic potential on the properties of a strongly coupled polaron in an asymmetric Gaussian quantum well

The effect of a parabolic potential on the properties of a strongly coupled polaron in an asymmetric Gaussian quantum well

Effect of the anisotropic parabolic potential on the polaron’s properties in asymmetric Gaussian quantum wells

In the current study, the linear combination operator (LCO) and Lee–Low–Pines unitary transformation (LLPUT) are adopted to verify the effect of the anisotropic parabolic potential (APP) on the polaron’s properties in the asymmetric Gaussian quantum well (AGQW). Relations of the vibrational frequency (VF) and the ground state energy (GSE) of weak coupling polaron in the AGQW for GaAs crystal varying with the effective confinement strengths of the APP, the barrier height, and range of the asymmetric Gaussian confinement potential (AGCP) are derived. The numerical calculated results illustrate that the GSE and VF of the weak coupling polaron in the AGQW can increase according to the effective confinement strengths’ growth for given values of the barrier height and range of the AGCP. They will increase by increasing the barrier height of the AGCP. However, they are decreasing functions of the range of the AGCP for the determined values of the effective confinement strengths and the barrier height of the AGCP.

Electronic features of Gaussian quantum well as depending on the parameters

In this study, the electronic characteristics of Gaussian quantum well have been examined as dependent on the parameters such as the concentration ratio, the even power parameter and Gaussian potential range. The energy levels and the wave functions in Gaussian quantum well (GQW) under effective mass approach were concluded by Schrödinger equation solution. According to our results, all parameters have a great impact on the electronic characteristics of GQW. These characteristics have practical interest in the design of adjustable semiconductor devices using such structures.

Temperature effects on state-energy levels and transition frequency of magnetopolaron in asymmetric two-dimensional Gaussian quantum wells

Influence of the magnetic field on the energy levels and the excitation energy (EE) between the two states of the magnetopolaron strongly coupled in asymmetric Gaussian quantum wells is examined by the variational method of Pekar type. Then, we discover the temperature and magnetic field effects on the energy levels and EE with quantum statistics theory. According to the results of the article, the energy levels and the EE are a function relationship with the temperature rising and magnetic field increasing.

Effect of temperature on lifetime and energy states of bound polaron in asymmetrical Gaussian quantum well

In this work, we have investigated the effect of temperature on the ground state energy, first excited state energy and the lifetime of bound polaron in an asymmetrical Gaussian quantum well. In this regard, we have used the well-known Lee–Low–Pines unitary transformation method and the Pekar type variational procedure. We have also discussed the influence of the Coulomb bound parameter and the electron–phonon coupling strength on the energy states, the phonons mean number and the lifetime. It is found that the ground and first excited state energies increase with raising temperature. The energy change of states decreases with increasing the Coulomb bound parameter and the electron-phonon coupling strength. The lifetime of bound polaron is a decreasing function of temperature. It is observed that the range and the height of Gaussian potential well are important characterizations to study the energy levels and lifetime of strong-coupling polaron in an asymmetrical Gaussian quantum well.

Improvement of the quantum confined Stark effect characteristics by means of energy band profile modulation: The case of Gaussian quantum wells

We study the quantum confined stark effect (QCSE) characteristics in Gaussian quantum wells (GQW). This special energy band profile is built varying the aluminum concentration of the AlGaAs ternary alloy in Gaussian fashion. The semi-empirical sp3s* tight-binding model including spin is used to obtain the energy Stark shifts (ESS) and the wave-function Gaussian spatial overlap (GSO) between electrons and holes for different electric field strengths, quantum well widths and aluminum concentrations. We find that both the ESS and the GSO depend parabolically with respect to the electric field strength and the quantum well width. These QCSE characteristics show an asymmetry for the electric field in the forward and reverse directions, related directly to the different band-offset of electrons and holes, being the negative electric fields (reverse direction) more suitable to reach greater ESS. Two important features are presented by this special energy band profile: (1) reductions of the ESS and (2) enhancements of the GSO of tents to hundreds with respect to parabolic and rectangular quantum wells. Even more, tailoring the quantum well width it is possible to reach GSO of thousands with respect to rectangular quantum wells. Finally, it is important to mention that similar results could be obtained in other quantum well heterostructures of materials such as nitrides, oxides (ZnO), and SiGe whenever the confinement band profiles are modulated in Gaussian form.

Confined exciton-polaritons in parabolic and Gaussian quantum wells

In order to study the confined polaritons in gradual quantum structures we have calculated the exciton binding energies of parabolic and Gaussian quantum wells using a variational perturbative approach. In the linear regime, we have established, by means of the semi-classical theory, the dispersion modes of a polariton confined in quantum wells, where the confining potentials are parabolic and Gaussian. In fact, we have evaluated the oscillator strength of each quantum well in order to get an idea about the confinement size and we have concluded that the polariton is more confined in a Gaussian quantum well than in a parabolic quantum well. To make a complete description of the confined polariton we have taken into account the electron - hole exchange energy. Numerical results show that the largest effect arising from the exciton - radiation interaction is the ZT and LT splittings, which strongly depend on the quantum confinement.