The effect of hydrostatic pressure on binding energy and polaron effect of bound polaron in wurtzite AlyGa1−yN/AlxGa1−xN parabolic quantum well

Author(s):  
Feng Qi Zhao ◽  
Zi Zheng Guo ◽  
Bo Zhao

The effect of hydrostatic pressure on binding energy and polaron effect of the bound polaron in a wurtzite Al[Formula: see text]Ga[Formula: see text]N/Al[Formula: see text]Ga[Formula: see text]N parabolic quantum well (QW) is studied using the Lee–Low–Pines intermediate coupling variational method in the paper. The numerical relationship of binding energy and polaron effect of the bound polaron are given as a functions of pressure [Formula: see text], composition [Formula: see text] and well width [Formula: see text]. In the theoretical calculations, the anisotropy of the electron effective band mass, the optical phonon frequency, the dielectric constant and other parameters in the system varying with the pressure [Formula: see text] and the coordinate [Formula: see text] are included. The electron–optical phonon interaction and the impurity center–optical phonon interaction are considered. The results show that hydrostatic pressure has a very obvious effect on binding energy and polaron effect of the bound polaron in the wurtzite Al[Formula: see text]Ga[Formula: see text]N/Al[Formula: see text]Ga[Formula: see text]N parabolic QW. For QWs with determined structural parameters, the contributions of the three branch of phonons, i.e., the confined (CF) phonon, half-space (HS) phonon and the interface (IF) phonon, to binding energy of the polaron increase with the increase of the pressure [Formula: see text], the CF phonons contribute the most. Under the condition of a certain well width and hydrostatic pressure, with the increase of the composition [Formula: see text], the ground state binding energy of the bound polaron in the wurtzite Al[Formula: see text]Ga[Formula: see text]N/Al[Formula: see text]Ga[Formula: see text]N parabolic QW increases, and the contribution of the IF phonon and HS phonons to the binding energy decreases, while the contribution of the CF phonons and the total contribution of all phonons increase significantly. In the wurtzite Al[Formula: see text]Ga[Formula: see text]N/Al[Formula: see text]Ga[Formula: see text]N parabolic QW, the ground state binding energy of the bound polaron decreases with the increase of the well width. The decrease rate is greater in the narrow well, and smaller in the wide well. The contribution of different branches of phonons to binding energy varies with the change of the well width. With the increase of the well width, the contribution of CF phonons to binding energy increases, the contribution of HS phonons to binding energy decreases, and the IF phonon contribution and the total phonon contribution first increase to the maximum value and then gradually decrease slightly. The changing trend of binding energy of bound polaron in the wurtzite Al[Formula: see text]Ga[Formula: see text]N/Al[Formula: see text]Ga[Formula: see text]N parabolic QW, of the contribution of different branch phonons to binding energy with the pressure [Formula: see text], composition [Formula: see text] and well width [Formula: see text] is similar to that of the GaN/Al[Formula: see text]Ga[Formula: see text]N square QW, but the change in the parabolic QW is more obvious.

2001 ◽  
Vol 15 (20) ◽  
pp. 827-835 ◽  
Author(s):  
FENG-QI ZHAO ◽  
XI XIA LIANG

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.


2005 ◽  
Vol 19 (25) ◽  
pp. 3861-3868 ◽  
Author(s):  
P. NITHIANANTHI ◽  
K. JAYAKUMAR

The effect of Γ-X crossover due to the external hydrostatic pressure on the ground state donor binding energy as well as for some low lying excited states for a Quantum well has been investigated by considering the non-parabolicity of the conduction band and pressure dependent spatial dielectric screening. It is observed that the effect of Γ-X crossover is predominant for ground state than for low lying excited states.


2012 ◽  
Vol 629 ◽  
pp. 145-151
Author(s):  
Ren Tu Ya Wu ◽  
Qi Zhao Feng

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.


2008 ◽  
Vol 22 (12) ◽  
pp. 1923-1932
Author(s):  
JIA LIU ◽  
ZI-YU CHEN

The influence of a perpendicular magnetic field on a bound polaron near the interface of a polar–polar semiconductor with Rashba effect has been investigated. The material is based on a GaAs / Al x Ga 1-x As heterojunction and the Al concentration varying from 0.2 ≤ x ≤ 0.4 is the critical value below which the Al x Ga 1-x As is a direct band gap semiconductor.The external magnetic field strongly altered the ground state binding energy of the polaron and the Rashba spin–orbit (SO) interaction originating from the inversion asymmetry in the heterostructure splitting of the ground state binding energy of the bound polaron. How the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity and the electron area density have been shown in this paper, taking into account the SO coupling. The contribution of the phonons are also considered. It is found that the spin-splitting states of the bound polaron are more stable, and, in the condition of weak magnetic field, the Zeeman effect can be neglected.


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