Tuesday, 31 May 2022: 14:00
West Meeting Room 117 (Vancouver Convention Center)
Trivalent rare earth ions efficiently emit luminescence in amorphous silicon based alloy hosts. The luminescence details depend mostly on the immediate chemical neighborhood of the ions. In crystals, the high resolution luminescence peaks at low temperatures can be adjusted by lorentzian lineshapes, with energies determined by the symmetry of the well defined lattice sites. In disordered materials, however, not only the symmetry can change but also the local stoichiometry is not well defined. As a result the luminescence peaks present gaussian shape and often overlap. Nevertheless, by carefully adjusting the luminescence spectra, one can obtain the energies corresponding to the allowed transitions and infer the local geometry. We studied the luminescence of Eu3+ and Tb3+ in hydrogenated amorphous silicon nitride at low temperatures. The results indicate that Eu3+ is mostly on cubic-like sites, while Tb3+ can be found both in different symmetries. This confirms that in general rare earth ions coordinate to any residual oxygen they can bind to during sample preparation. The chemical environment of the rare earth ions is probably determined by the local chemistry rather than imposed by the network.