Inhomogeneous free-electron distribution in InN nanowires: Photoluminescence excitation experiments

Photoluminescence excitation (PLE) spectra have been measured for a set of self-assembled InN nanowires (NWs) and a high-crystalline quality InN layer grown by molecular-beam epitaxy. The PLE experimental lineshapes have been reproduced by a self-consistent calculation of the absorption in a cylindrical InN NW. The differences in the PLE spectra can be accounted for the inhomogeneous electron distribution within the NWs caused by a bulk donor concentration (ND⁺) and a two-dimensional density of ionized surface states (Nₛₛ⁺). For NW radii larger than 30 nm, ND⁺ and Nₛₛ⁺ modify the absorption edge and the lineshape, respectively, and can be determined from the comparison with the experimental data.