Polaronic effect on the electron energy spectrum in a wurtzite In _xGa_(1-x)n/GaN quantum well

摘要

The properties of polarons in wurtzite and zinc-blende In _xGa_(1-x)N/GaN quantum wells are investigated by adopting an effective-mass approximation and a modified Lee-Low-Pines variational method. The energy shifts of polarons at ground state due to the confined, half-space and interface phonon modes (including symmetric and antisymmetric parts), as well as the ground state energy and transition energy, are obtained by a numerical computation. The results indicate that both ground state energy and transition energy of polarons decrease monotonically with increasing the well width. For a wider quantum well, the total contribution to the polaron energy mainly comes from the confined phonon modes, while for a narrower one, the total contribution is mainly from the interface and half-space phonon modes. The built-in electric field has a remarkable effect on the polaron energy shifts contributed by various phonon modes. It can be also found that the polaronic effect in In_xGa_(1-x)N/GaN quantum wells is much stronger than that in conventional zinc-blende quantum wells composed by arsenide compounds.