Effects of pressure on polaron energy shift in a wurtzite AlyGa1-yN/AlGa1-xN parabolic quantum well

摘要

The effect of hydrostatic pressure on the energy level of polaron and polaron energy shift in wurtzite AlyGa1-yN/AlxGa1-xN parabolic quantum well (QW) is studied by a variational method. The numerical results of the ground state energy, transition energy and contributions of different phonons to polaron energy (polaron energy shift) are given as functions of pressure p, well width d, and composition x. In the theoretical calculation, the anisotropy of the parameters, such as the phonon frequency of different optical branches, the electron effective mass, the dielectric constant, etc., and their pressure and coordinate dependence are considered. The results show that the energy and transition energy of the polaron in the wurtzite AlyGa1-yN/AlxGa1-xN parabolic QW decrease with the increasing of the hydrostatic pressure p and the well width d, and increase with the increasing of the composition x. The trends of the polaron energy shift with pressure p, well width d and composition x are obviously different. With the increase of hydrostatic pressure, the contribution of interface (IF) phonon slowly increases, while the contribution of confined (CF) phonon, half-space (HS) phonon and the total contribution of phonons of all branches increases obviously. During the increase of the well width, the contribution of CF phonon increases, and the contribution of HS phonon decreases, while the contribution of IF phonon and total contribution of phonons of all branches increase first and then decrease. With increasing the composition, the contribution of HS phonon decreases and the contribution of IF phonon increases slowly, while the contribution of CF phonon and the total contribution of phonons of all branches phonon increase significantly. The dependences of hydrostatic pressure, well width,and composition x of the ground state energy, transition energy, and polaron energy shift of the polaron in the wurtzite AlyGa1-yN/AlxGa1-xN parabolic QW structure are basically similar to