Site of Er ions in silica layers codoped with Si nanoclusters and Er

Abstract

Silica layers implanted with Si and Er ions to various doses and annealed at 950°C have been investigated by means of energy-filtered transmission electron microscopy (EFTEM) and high annular angle dark field (HAADF). EFTEM analysis reveals Si nanoclusters (Si-nc) with an average size around 3nm for high Si content (15at.%) whereas no clusters can be imaged for the lowest Si excess (5at.%). Raman scattering supports that amorphous Si precipitates are present in all the samples. Moreover, the filtered images show that Er ions appear preferentially located outside the Si-nc. HAADF analysis confirms that the Er atoms form agglomerations of 5–10nm size when the Er concentration exceeds 1×1020cm−3. This observation correlates well with the reduction of the Er population excitable by Si nanoclusters, in the best case corresponding to 10% of the total. A suitable tuning of the annealing drastically reduces this deleterious effect.

Limit to the erbium ions emission in silicon-rich oxide films by erbium ion clustering

“…It is worth mentioning that similar local inhomogeneity in erbium ions spatial distribution and the tendency to clusterize in silicon rich oxide films have been reported previously in thin films prepared with very different deposition techniques [20][21][22][23][24]. Thus, this type of behavior is not inherent to LPCVD but is quite general for Er 3+ concentrations larger than 10 20 at./cm 3 [20][21][22][23][24].…”

On the interplay between Si-Er-O segregation and erbium silicate (Er2Si2O7) formation in Er-doped SiOx thin films

“…For all samples, no signal of Er 3þ ions at 1.54 mm has been detected, evidencing a quenching of the luminescence as usually observed for high doping level of silicon rich silica and high temperature annealing [8,17,21]. Fig.…”

“…Accordingly, an understanding of luminescence requires the control of the structural evolution. However, the study of the nanoscale structure of these systems has only been slightly studied [8,21,22] and consequently the precipitation mechanism of the Er ions in SRSO remains very poorly understood. Hence, our samples were subjected to 1 h heat treatment at 1100 + C, a temperature for which Si-ncs in silica should be formed [12] and thus be able to sensitize efficiently the Er ions [17].…”

“…Moreover, many questions persist about the spatial localization of the optically active Er 3þ ions with respect to the Si nanoparticles. Specifically, either these ions are uniformly distributed, or they form agglomerates [8]. Therefore, mapping the Si and Er atoms distribution and the phase present in the sample with respect to elaboration and heat treatment conditions are key issues in controlling the required emission properties of such systems.…”

Metal island film-based structures for sensing using spectrophotometry and ellipsometry

“…In order to obtain the average grain size and nanoparticle morphology Bright field (BF) transmission electron microscopy (TEM) images are done in a Jeol 2010F field emission gun microscope operated at 200 KV. In order to differentiate between Si and SiO2 and achieve clear composition images, energy filtered TEM (EFTEM) is made [16,17].…”