Polaron effects due to interface optical‐phonons in wurtzite GaN/AlN quantum wells

Abstract

Considering the effects of the built-in electric field (BEF) induced by the spontaneous and piezoelectric polarizations of wurtzite GaN/AlN quantum wells (QW's), the polaron energy shift and the effective mass due to the electron interactions with the interface optical-phonons are investigated theoretically by means of Lee-Low-Pines variational approach. We find that the BEF has a remarkable influence on the polaron effects especially for a QW with well width d > 6 nm. The polaron energy shift increases slowly and its effective mass approaches to a constant if d is further increased. On the contrary, both the polaron energy shift and the effective mass decrease slowly with the increasing of d if the BEF is ignored.

Confinement of polar optical phonons in quasi-one-dimensional Wurtzite GaN-based quantum well wires: propagating and half-space phonon modes

“…Because of the importance of the dispersive frequencies of the free wave-number k z and azimuthal quantum-number m for further investigating the polaronic effect on the physical properties of the QWW structures [36,[39][40][41], we have computed and analyzed the dispersion properties of the PR and HS phonon modes on k z and m for a Q1D wurtzite Al 0.15 Ga 0.85 N/GaN/Al 0.15 Ga 0.85 N QWW in this section. The geometrical sizes of the QWW are as follows: the inner radius R 1 = 2a B , and the outer radius R 2 = 4a B (a B is the effective Bohr radius of wurtzite GaN material, which equals about 2.4 nm).…”

“…Moreover, we find that the coupling strength between electrons with HS-Hi modes is stronger than that between electrons with HS-Li ones for certain k z and m in general. These dispersive features and electron-phonon coupling properties of phonon modes will contribute to the further investigation of phonon effects on the physical properties of Q1D QWW systems [36,[39][40][41].…”

POLAR VIBRATION SPECTRA OF INTERFACE AND SURFACE OPTICAL PHONONS AND THEIR FRÖHLICH ELECTRON-PHONON INTERACTIONS IN FREESTANDING SYMMETRICAL AND ASYMMETRICAL WURTZITEGaN/Ga1-xAlxNMULTI-LAYER HETEROSTRUCTURES

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] These nitride materials are also quite attractive from a purely physical viewpoint. Their fundamental physical properties can be largely affected and even determined by the spatial quantization of the electron states, the anisotropy of the crystal structures, the symmetry of the heterostructures and the dielectric environments.…”

“…The group-III nitrides usually crystallize in wurtzite structure, which results in their phonon spectra being much more complex due to anisotropy of the crystal structure compared with phonons in cubic crystals. [6][7][8][9][10][11][12][13][14][15] It is well known that, at room and higher temperatures, the electron-phonon interactions and scattering play an important role for various properties of polar semiconductor quantum heterostructures, including hot-electron relaxation rates, interband transition rates, room-temperature exciton lifetimes, and many other optical and transport properties. Hence, the understanding of lattice dynamics and electron-phonon interactions in wurtzite quantum heterostructures has not only an important theoretical meaning, but also practical significance for device applications.…”

“…[6][7][8][9][10][11][12][13][14][15] For example, Komirenko et al 6 investigated the dispersion of polar optical phonons in symmetrical wurtzite AlN/GaN/AlN and Al 0.15 Ga 0.85 N/GaN/Al 0.15 Ga 0.85 N quantum wells (QWs), and the interface optical (IO) phonon modes, the confined modes, the propagating modes and the half-space (HS) modes were discussed. Gleize and co-workers 7 analyzed the anisotropy effects on the polar optical phonons in wurtzite AlN/GaN single QWs and superlattices.…”