Quantum size effect on the luminous properties of excitonic states in a quasi-one-dimensional wurtzite GaN nanowire: Two-parameter variational approach

In order to reflect the anisotropic confined situations of quasi-one-dimensional (Q1D) wurtzite nanowires (NWs) in axial and radial directions and wurtzite GaN crystal, a two-parameter variational approach is brought forward and applied to investigate luminous properties of excitonic states in wurtzite NW systems. Numerical calculations on a GaN NW are performed. The quantum size effect on the excitonic binding energies of ground states, the ground state energies as well as the emission spectra is analyzed in detailed. Both the light hole excitons and heavy hole excitons in wurtzite NWs are taken in account. The calculated excitonic binding energies in the wurtzite GaN NWs are far larger than those in cubic GaAs-based quantum wires with the same radius. This is mainly ascribed to the large effective masses of electron and hole and relatively small dielectric constants in GaN material. The excitons emission wavelengths calculated here qualitatively agree with recent experimental results of exciton luminous spectra in Q1D GaN NWs. This confirmed the reasonability and reliability of the present theoretical scheme and numerical results. The numerical results also show that the two-parameter variational approach is reasonable and necessary for the description of excitonic states in Q1D wurtzite GaN NWs.