Polarized light absorption in wurtzite InP nanowire ensembles.

De Luca, Marta; Zilli, Attilio; Fonseka, H Aruni; Mokkapati, Sudha; Miriametro, Antonio; Tan, Hark Hoe; Smith, Leigh Morris; Jagadish, Chennupati et al. · Nano Lett · 2015

basic_science · Level V

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Abstract

We investigate the absorption properties of ensembles of wurtzite (WZ) InP nanowires (NWs) by high-resolution polarization-resolved photoluminescence excitation (PLE) spectroscopy at T = 10 K. The degree of linear polarization of absorbed light, ρ(abs), resulting from the PLE spectra is governed by a competition between the dielectric mismatch effect and the WZ selection rules acting differently on different optical transitions. These two contributions are deconvoluted with the help of finite-difference time-domain simulations, thus providing information about the symmetry of the three highest valence bands (A, B, and C) of WZ InP and the extent of the spin-orbit interaction on these states. Moreover, ρ(abs) shows two characteristic dips corresponding to the two sharp A and B exciton resonances in the PLE spectra. A model developed for the dip in A provides the first experimental evidence of an enhancement in the dielectric mismatch effect originating from the Coulomb interaction between electron and hole.