Energy Of The Bound Polaron In Wurtzite GaN/Al_xGa_1-xN Quantum Well

The research of theâ…¢-N andâ…¢-V-N compound which rose in the mid-90s has infused the new vitality for the semiconductor photoelectric apparatus's development. Nitrogen semiconductor (AlN and GaN, InN, AlGaN, GaInN) materials, because of their unique physical properties, are more advantage than silicon and gallium arsenide in the short-wave photonics, optical detector (blue, green and ultraviolet light), high-frequency high power and high temperature devices.Based on the electron-phonon interaction Hamiltonian in wurtzite GaN/AlxGa1-xN quantum wells, the energy levels of the bound polaron is researched in this paper. The energy and the binding energy of the ground state, first excited state energy and binding energy,and the transition energies from first excited state to ground state of the bound polaron in the wurtzite GaN/AlxGa1-xN quantum well structure are calculated as a function of well width L and depth V0(or composition x). The electron - phonon interaction is processed by using LLP (Lee-Low-Pines) two unitary transformations in theoretical derivation.The numerical results indicate that the ground state energy and binding energy,first excited state energy and binding energy,and the transition energy from first excited state to ground state of the bound polarons in the wurtzite GaN/AlxGa1-xN quantum well rapidly decrease with increasing the well width at smaller L,but slowly at larger L,and finally approach to the bulk value of GaN. The ground state energy and binding energy,first excited state energy and binding energy,and the transition energy from first excited state to ground state of the bound polarons in the wurtzite GaN/AlxGa1-xN quantum well all slowly increase with increasing V0,and it is more visible in narrow well. It is also found that the contribution of electron-phonon interaction in wurtzite GaN/Al0.3Ga0.7N quantum well structure is very large , the value(about 40mev) is much larger than that(about 3mev)in GaAs/Al0.3Ga0.7As quantum well structure. Therefore,the contribution of electron-phonon interaction in wurtzite GaN/AlxGa1-xN quantum well structure should be considered when the election state in wurtzite GaN/AlxGa1-xN quantum well is discussed. For the qualitative analysis and comparison, the paper also gives the energies of the bound polarons as functions of well width L in the infinite quantum well when the electron-phonon interaction is considered. The ground-state energy,the first excited state energy,the binding energy and the transition energy from first excited state to ground state of the bound polaron in the infinite quantum well are significantly larger than the corresponding values in the finite quantum well at smaller well widths, but the corresponding values are almost the same in these two kind of quantum wells at large well widths.