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

Abstract

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.