On the interplay between Si-Er-O segregation and erbium silicate (Er 2 Si 2 O 7 ) formation in Er-doped SiO x thin films

International audienceEr-doped silica or rich-silicon oxide has been widely studied as 1.54 mm emitters. The incorporation of Si-nanoclusters is known for improving luminescence yield of Er 3þ ions through an efficient sensitization of the neighboring rare earth ions. The aim of this work is to investigate the influence of Silicon excess and Erbium concentration on the formation of silicon nanoclusters and Er-rich phase responsible of the quenching of 1.54 mm emission. Atom probe tomography and photoluminescence spectroscopy were used to explore the nanostructure and optical activity of Er-doped silicon rich silica. We present a direct evidence that both silicon excess and Er concentration influence the growth of Si nanoclusters, the formation of Er-Si-O phase and the luminescence of both Si nanoclusters and Er 3þ ions. We explain these finding in relation with the growth mechanism of nanoparticles and the presence of a Snowman-like Janus morphology between silicon and Erbium silicates nanoparticles. In this contribution, we deciphered the nanoscale structure spatial correlations between Er and Si atoms in Er doped SiO X which remained unclear for a long time

Effect of rapid thermal treatments on the physical properties of Cobalt Doped ZnO Films

International audienc

Concentration determination and activation of rare earth dopants in zinc oxide thin films

International audienceIn this paper, we will present the development of rareearth(RE) doped zinc oxide (ZnO) films for white lightemitting diodes (LED). We will present the structuralchanges of these films as well as their optical propertiesand associated photoluminescence before and after rapidthermal treatments. We will report depth profile resultsfrom plasma profiling time of flight mass spectrometry(PP-TOFMS) giving the distributions and concentrationsof the different elements in the films. We will correlatedepth profile and luminescence data to understand the REemission mechanisms in ZnO matrix

Two components for one resistivity in LaVO3/SrTiO3 heterostructure

10.1088/0953-8984/27/9/095603Journal of Physics Condensed Matter27

Comprehensive investigation of Er2O3 thin films grown with different ALD approaches

International audienceThe effect of Er precursor nature (Er(CpMe)3 or Er(tmhd)3) and annealing treatment at 500-1100°C on the structural and optical properties of Er2O3 films grown on Si substrates by thermal or O2-plasma-assisted atomic layer deposition (ALD) was studied by means of spectroscopic ellipsometry, Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy coupled with energy dispersive X-ray spectroscopy as well as photoluminescence method. An annealing at 500-800°C results in the film crystallization mainly. Thermal treatment at high temperatures causes the formation of Er silicate phase due to the diffusion of Si atoms from the substrate in the films depth. This phase was found to be Er2SiO5 being crystallized at 1100°C. Light emitting properties of the films are determined by Er2O3 native defects (like oxygen vacancies) and intra-4f shell transition in Er3+ ions. The latter dominates in the films annealed at 1000-1100°C. The most intense Er3+ emission, observed in the films grown with O2-plasma-assisted ALD approach, was explained by a lower contribution of oxygen vacancies as well as by pronounced crystallization of Er silicate phase. In this latter the effect of concentration quenching of Er3+ luminescence was lower due to a larger distance between Er3+ neighbor ions

Influence of post annealing treatments on the luminescence of rare earth ions in ZnO:Tb,Eu/Si heterojunction

International audience(Tb, Eu)–co-doped ZnO films with about 3 at.% total doping rate were grown by magnetron sputtering on Si substrate. Post annealing treatments were performed at 973–1373 K in continuous nitrogen flow to investigate the transformation of microstructural and optical characteristics by means of X-ray diffraction, transmission electron microscopy, photoluminescence and electroluminescence. For annealing temperatures lower than 1073 K, segregation of Eu and Tb was observed mainly at the film/substrate junction. For temperatures higher than 1173 K, additional phases appeared, namely, Zn2SiO4 and rare earth silicates. For the highest temperature investigated (1373 K), only silica and rare earth silicates remained in the film due to Zn evaporation. PL measurements indicated a very intense Eu emission associated with the presence of rare earth silicate inclusions. Energy transfer from Tb towards Eu was evidenced in this secondary phase. At last, based on these preliminary works, a (Tb, Eu)–co-doped ZnO/Si electroluminescent structure was produced and showed very promising results paving the way for very thin ZnO based light emitting diodes

Dispositifs Appliqués à la Photonique à base de Néodyme et de Silicium

posterNational audienc

Dispositifs Appliqués à la Photonique à base de Néodyme et de Silicium

posterNational audienc

Thermally induced evolution of optical and structural properties of Er2O3 films grown on Si substrates by thermal atomic layer deposition

International audienceThermally induced evolution of structural and optical properties of Er 2 O 3 films prepared by atomic layer deposition was investigated. The films were grown on Si substrates by water-assisted approach from (tris (methylcyclopentadienyl)erbium(III). As-deposited films showed cubic Er 2 O 3 phase, and compressive stress. Isochronal (30 min) heating at 600-1100°C in nitrogen flow caused strain relaxation, decrease of the lattice parameters and the increase of coherent domain size. Besides, in the films annealed at 1000-1100°C, the formation of Er silicate phase was observed. This phase formed due to Si diffusion from substrate in film volume, and the presence of Si was found not only at the film/substrate interface, but also on the top surface of the film. This fact was explained by spinodal decomposition of Er silicate with the formation of Er 2 SiO 5 phase on top surface. It was shown that both oxygen vacancies and Er 3+ ions contribute to light emission, however, no energy transfer from vacancies to Er 3+ ions was detected