Observation of anomalously polarized photoluminescence in alternating nanocrystalline Si-amorphous Si multilayers

Polarization properties of visible photoluminescence (PL) from alternating hydrogenated nanocrystalline silicon-amorphous silicon multilayers excited with linearly polarized light are examined. The PL is almost linearly polarized in the direction perpendicular to the polarization of excitation light, independent of the sample orientation. The degree of linear polarization δ negatively increases with decreasing emission energy, reaching a maximum of ∼90% on the low-energy side, and a different temperature dependence is observed. In addition, it was found that the sample with large structural inhomogeneity displays low PL efficiency and large δ. Since the obtained PL spectra show no crystallite size dependence of the peak energy and fine structures, we attribute these anomalous polarization properties to the radiative recombination of carriers confined in the interfacial region of optically anisotropic and randomly distributed Si:H nanocrystals.