Polaronic self-trapped energy and effective mass of a cylindrical wurtzite GaN nanowire

Abstract

The ground-state self-trapped energy and effective mass of the polaron in a freestanding wurtzite GaN nanowire (NW) are studied by employing the perturbation approach. Based on the dielectric continuum model and the Loudon uniaxial crystal model, the full polar optical phonon modes, i.e. quasi-confined (QC) phonon modes and surface optical (SO) phonon modes, in the one-dimensional (1D) wurtzite systems have been analyzed. The vibrating spectra of the two types of phonon modes and their electron–phonon coupling properties have been discussed and analyzed. The numerical results on the ground-state polaron self-trapped energy and correction of effective mass in the 1D GaN NWs reveal that these are far larger than those in 1D GaAs NW systems. The reasons resulting in this obvious difference in the two 1D structures can be attributed to the different electron–phonon coupling constants and electron effective masses of bulk materials constituted of the two types of 1D confined systems. Moreover, our calculated results regarding the polaronic self-trapped energy are consistent with the recent experimental observation in GaN NW systems.