POLARONIC EFFECTS IN WURTZITE GaN/AlxGa1-xN QUANTUM WELLS

2011 ◽  
Vol 25 (15) ◽  
pp. 2105-2114 ◽  
Author(s):  
FENG-QI ZHAO ◽  
MIN ZHANG
Keyword(s):  
Quantum Wells ◽  
Ground State Energy ◽  
Optical Phonon ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Phonon Modes ◽  
Optical Phonon Mode ◽  
Total Contribution ◽  
Numerical Result

The properties of polarons in a wurtzite GaN / Al x Ga 1-x N quantum well (QW) are investigated by adopting an effective-mass approximation and a modified Lee–Low–Pines variational method. The ground-state energy, the transition energy and the phonon contributions due to various optical-phonon modes to the ground-state energy as functions of the well width are given. The effects of the confined (CF) optical phonon mode, interface (IF)-optical phonon modes, half-space (HS) phonon modes, the anisotropy of the electron effective band mass and the phonon frequency are respectively considered (or included) in the calculation. The results have been compared with those of the zinc-blende structure. The numerical result indicates that both the ground-state energies of polaron and the transition energy decrease with increasing well width. For QWs with larger well width (> 10 nm), the total contribution to polaronic energy mainly comes from the confined mode, and for QWs with narrower well width (< 2 nm), the total contribution to polaronic energy mainly comes from the IF-optical phonon and HS phonon modes. And the phonon contribution in GaN/Al x Ga 1-x N QW is much larger than that in GaAs/Al x Ga 1-x As QW. The two IF-optical phonon modes with lower frequency, the transverse optical-like CF and HS modes are extremely small so that they can be neglected in the further discussion.

Polaronic Effects in Wurtzite InxGa1-xN/GaN Parabolic Quantum Well

2012 ◽  
Vol 629 ◽  
pp. 145-151
Author(s):  
Ren Tu Ya Wu ◽  
Qi Zhao Feng
Keyword(s):  
Quantum Well ◽  
Ground State Energy ◽  
Optical Phonon ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Energy Levels ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Zinc Blende

The energy levels of polaron in a wurtzite InxGa1-xN/GaN parabolic quantum well are investigated by adopting a modified Lee-Low-Pines variational method. The ground state energy, the transition energy and the contributions of different branches of optical phonon modes to the ground state energy as functions of the well width are given. The effects of the anisotropy of optical phonon modes and the spatial dependence effective mass, dielectric constant, phonon frequency on energy levels are considered in calculation. In order to compare, the corresponding results in zinc-blende parabolic quantum well are given. The results indicate that the contributions of the electron-optical phonon interaction to ground state energy of polaron in InxGa1-xN/GaN is very large, and make the energy of polaron reduces. For a narrower quantum well，the contributions of half-space optical phonon modes is large , while for a wider one, the contributions of the confined optical phonon modes are larger. The ground state energy and the transition energy of polaron in wurtzite InxGa1-xN/GaN are smaller than that of zinc-blende InxGa1-xN/GaN, and the contributions of the electron-optical phonon interaction to ground state energy of polaron in wurtzite InxGa1-xN/GaN are greater than that of zinc-blende InxGa1-xN/GaN. The contributions of the electron-optical phonon interaction to ground state energy of polaron in wurtzite InxGa1-xN/GaN (about from 22 to 32 meV) are greater than that of GaAs/AlxGa1-xAs parabolic quantum well (about from 1.8 to 3.2 meV). Therefore, the electron-optical phonon interaction should be considered for studying electron state in InxGa1-xN/GaN parabolic quantum well.

Influence of Pressure on Polaron Energy in a Wurtzite GaN/AlxGa1-xN Quantum Well

2019 ◽  
Vol 288 ◽  
pp. 17-26
Author(s):  
Feng Qi Zhao ◽  
Xiao Mei Dai
Keyword(s):  
Hydrostatic Pressure ◽  
Quantum Well ◽  
Quantum Wells ◽  
Half Space ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Total Contribution ◽  
Polaron Energy

The influence of hydrostatic pressure on the polaron energy level in wurtzite GaN/AlxGa1-xN quantum well is studied by a Lee-Low-Pines variational method, and the numerical results of the ground state energy, transition energy and contributions of different phonons to polaron energy (polaron effects) are given as functions of pressurepand compositionx. The results show that the ground state energy and transition energy in the wurtzite GaN/AlxGa1-xN quantum well decrease with the increase of the hydrostatic pressurep, and increase with the increase of the compositionx. The contributions of different phonons to polaron energy with pressurepand compositionxare obviously different. With the increase of hydrostatic pressure, the contribution of half-space phonon, confined phonon and the total contribution of phonons of all branches increases obviously, while the contribution of interface phonon slowly increases. During the increase of the composition, the contribution of interface phonon decreases and the contribution of half-space phonon increases slowly, while the contribution of confined phonon and the total contribution of phonons increases significantly. In general, the electron-optical phonon interaction play an important role in electronic states of GaN/AlxGa1-xN quantum wells and can not be neglected.

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

2021 ◽  
Author(s):  
Saren Gaowa ◽  
Yan-Bo Geng ◽  
Zhao-Hua Ding ◽  
Jing-Lin Xiao
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
Barrier Height ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Cyclotron Frequency ◽  
Strongly Coupled ◽  
Parabolic Potential ◽  
Do So

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.

BINDING ENERGY OF A BOUND POLARON IN THE FINITE PARABOLIC QUANTUM WELL

2001 ◽  
Vol 15 (20) ◽  
pp. 827-835 ◽  
Author(s):  
FENG-QI ZHAO ◽  
XI XIA LIANG
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Transition Energy ◽  
Energy Levels ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Bound Polaron

We have studied the effect of the electron–phonon interaction on the energy levels of the bound polaron and calculated the ground-state energy, the binding energy of the ground state, and the 1 s → 2 p ± transition energy in the GaAs/Al x Ga 1-x As parabolic quantum well (PQW) structure by using a modified Lee–Low–Pines (LLP) variational method. The numerical results are given and discussed. It is found that the contribution of electron–phonon interaction to the ground-state energy and the binding energy is obvious, especially in large well-width PQWs. The electron–phonon interaction should not be neglected.

Electron–Interface–Phonon Interaction and Magnetopolaronic Impurity Transitions in Quantum Wells

1997 ◽  
Vol 11 (08) ◽  
pp. 991-1008 ◽  
Author(s):  
R. Chen ◽  
D. L. Lin
Keyword(s):  
Quantum Wells ◽  
Optical Phonon ◽  
Phonon Frequency ◽  
Transition Energy ◽  
Bulk Sample ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Double Heterostructure

The polaronic effect on the hydrogenic 1s–2p+ transition energy of a donor impurity located at the quantum well center in a double heterostructure is studied theoretically in detail. The electron–optical–phonon interaction Hamiltonian is derived on the basis of eigenmodes of lattice vibrations supported by the double heterostructure. Both the confined and interface phonon modes are included in the electron–phonon coupling. The transition energy is calculated as a function of the applied magnetic field for GaAs/Al 1-x Ga x As samples of well -widths d=125 Å, 210 Å and 450 Å by the second-order perturbation. Wide transition gaps are predicted around the two-level and three-level resonances for all three cases. It is found that the transition gap narrows with the increasing well-width but remains larger than the LO and TO phonon frequency difference for d=450 Å as is observed. We also perform the same calculation by assuming that the confined electron interacts with three-dimensional and two-dimensional phonon modes. The transition energy spectra from these calculations appear to be similar to those for a bulk sample, the spectrum splits at the resonance with the longitudinal optical phonon frequency only. From comparisons of our results with these calculations as well as with experiments, it is conclusively established that the wide gap of transition energy is solely due to the interface modes.

Many-body effects on the ground-state energy in semiconductor quantum wells

2004 ◽  
Vol 106 (2) ◽  
pp. 177-181
Author(s):  
M.R. Kim ◽  
C. Tong ◽  
S.K. Kim ◽  
M.S. Son ◽  
D.H. Shin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Many Body ◽  
Semiconductor Quantum Wells ◽  
Many Body Effects
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