The Effects Of The Electron-phonon Interaction To The Bound Polaron Energy In Wurtzite In_xGa_1-xN/GaN Quantum Well

The binding energy of bound polaron and the effects of theelectron-phonon interaction on the energy in wurtzite and zinc-blendeIn_xGa_1-xN/GaN(GaN/Al_xGa_1-xN)quantum well was investigated by usingmodified Lee-Low-Pines （LLP） variational method. The ground state energy,the binding energy and the contributions of the electron-optical phononinteraction on the energy in wurtzite and zinc-blende In_xGa_1-xN/GaN(GaN/Al_xGa_1-xN) quantum well are calculated as functions of well widthand composition In（Al）. The effects of confined phonon modes and interfacephonon modes, and the anisotropy of optical phonons frequency areconsidered in the calculation. The results show that the ground state energy,the binding energy of bound polaron in wurtzite and zinc-blendeIn_0.3Ga_0.7N/GaN (GaN/Al_0.3Ga_0.7N) quantum well decreases with increasingwell width d, and finally approaches to the bulk value of In_0.3Ga_0.7N （GaN）.The ground state energy of bound polaron in wurtzite quantum well aresmaller than that in zinc-blende quantum well, and the binding energy、thecontributions of the electron-phonon interaction to the energy of boundpolaron in wurtzite quantum well are larger than that in zinc-blende quantumwell. For different phonon modes, the contributions of the interface phononmodes on energy are larger than that of the confined modes for narrow wells,and the contributions rapidly decrease with increasing the well width, andapproach to zero. But the contributions of the confined modes rapidly increasewith increasing the well width d, and the contributions are larger than that ofthe interface modes at certain well width, and finally approach to totalcontributions. The contributions of electron-optical phonon interaction to theenergy of bound polaron is obviously large, it makes the ground state energyand the binding energy of bound polaron reduce. The contributions of the electron-optical phonon interaction to ground state energy of bound polaron inwurtzite In_0.3Ga_0.7N/GaN （about from24to36meV） are greater than that ofGaAs/Al_0.3Ga_0.7As quantum well （about from1.8to3.2meV）. Therefore, thecontributions of electron-optical phonon interaction in wurtziteIn_0.3Ga_0.7N/GaN (GaN/Al_0.3Ga_0.7N) quantum well structure should beconsidered. The results also show that the ground state energy of boundpolaron in In_xGa_1-xN/GaN (GaN/Al_xGa_1-xN) quantum well increases withincreasing the composition In（Al）, and it is more visible in narrow well, but itis slowly in large well width. Meanwhile, the binding energy and thecontributions of electron-optical phonon interaction to the bound polaronenergy in GaN/Al_xGa_1-xN quantum wells increases with increasing the Alcomposition, but the case is contrary in In_xGa_1-xN/GaN quantum wells. Inwurtzite In_0.3Ga_0.7N/GaN and GaN/Al_0.3Ga_0.7Nquantum well （given wellwidth8nm and26nm）, the binding energy of bound polaron decreases withincreasing the impurity position Z₀, and the contributions of the confinedmodes to the ground state energy decrease with increasing Z₀, but thecontributions of the interface modes increase with increasing Z₀. The totalcontributions of electron-optical phonon interaction slowly decrease withincreasing Z₀.