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The diffusion and activation of arsenic implanted into germanium at 40 keV with maximum concentrations below and above the solid solubility (8 x 1019 cm-3been studied, both experimentally and theoretically, after excimer laser annealing (λ = 308 nm) in the melting regime with different laser energy densities and single or multiple pulses. Arsenic is observed to diffuse similarly for different fluences with no out-diffusion and no formation of pile-up at the maximum melt depth. The diffusion profiles have been satisfactorily simulated by assuming two diffusivity states of As in the molten Ge and a non-equilibrium segregation at the maximum melt depth. The electrical activation is partial and decreases with increasing the chemical concentration with a saturation of the active concentration at 1 x 1020 cm-3, which represents a new record for the As-doped Ge system. [ABSTRACT FROM AUTHOR]

The comparison of the performances of SiO2 and SiOC layers as host matrices for optically active Eu ions is presented. A SiO2 matrix allows to observe light emission from both Eu2+ and Eu3+ ions, owing to a proper tuning of the thermal annealing process used for the optical activation of the rare earth. However, the photoluminescence efficiency of both ions remains relatively low and quite far from the requirements for technological applications, mainly due to the extensive formation of Eu-containing precipitates. A detailed study by transmission electron microscopy allowed us to analyze and elucidate the clustering process and to find suitable strategies for minimizing it. We found that the substitution of SiO2 matrix with a SiOC film allows to obtain a very bright light emission centered at about 440 nm from Eu2+ ions. In fact, SiOC is able to efficiently promote the Eu3+ → Eu2+ reduction; furthermore, Eu ions are characterized by an enhanced mobility and solubility in this matrix, and as a consequence, Eu precipitation is strongly reduced. Since SiOC is a material fully compatible with standard Si technology, Eu-doped SiOC layers can be considered a highly interesting candidate for photonic applications. [ABSTRACT FROM AUTHOR]

An experimental and theoretical study of the effect of excimer laser annealing (ELA) on B redistribution and electrical activation in Ge is reported. We performed detailed structural, chemical, and electrical characterizations of Ge samples implanted with B (20 keV, 1 × 1015, or 1 × 1016 B/cm2) and processed by ELA (λ = 308 nm) with multiple pulses (1, 3, or 10). We also developed a diffusion model, in order to simulate the B redistribution induced by the ELA process. We found an anomalous impurity redistribution in the molten phase, which causes a dopant incorporation during the melt-growth at the maximum melt depth. The investigated samples showed a partial electrical activation of the B dopant. The inactivation of B in the samples implanted with 1 × 1015 B/cm2 was correlated to an oxygen contamination, while the poor electrical activation of B in the samples implanted with 1 × 1016 B/cm2 was related to the precipitation of the dopant, in good agreement with the experimental and theoretical results. [ABSTRACT FROM AUTHOR]

The enhanced diffusion of donor atoms, via a vacancy (V)-mechanism, severely affects the realization of ultrahigh doped regions in miniaturized germanium (Ge) based devices. In this work, we report a study about the effect of fluorine (F) on the diffusion of arsenic (As) in Ge and give insights on the physical mechanisms involved. With these aims we employed experiments in Ge co-implanted with F and As and density functional theory calculations. We demonstrate that the implantation of F enriches the Ge matrix in V, causing an enhanced diffusion of As within the layer amorphized by F and As implantation and subsequently regrown by solid phase epitaxy. Next to the end-of-range damaged region F forms complexes with Ge interstitials, that act as sinks for V and induce an abrupt suppression of As diffusion. The interaction of Ge interstitials with fluorine interstitials is confirmed by theoretical calculations. Finally, we prove that a possible F-As chemical interaction does not play any significant role on dopant diffusion. These results can be applied to realize abrupt ultra-shallow n-type doped regions in future generation of Ge-based devices. [ABSTRACT FROM AUTHOR]

In this paper we demonstrate that the structural and optical properties of Si nanoclusters (Si ncs) formed by thermal annealing of SiOx films prepared by plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering are very different. In fact, at a fixed Si excess and annealing temperature, photoluminescence (PL) spectra of sputtered samples are redshifted with respect to PECVD samples, denoting a larger Si ncs size. In addition, PL intensity reaches a maximum in sputtered films at annealing temperatures much lower than those needed in PECVD films. These data are correlated with structural properties obtained by energy filtered transmission electron microscopy and electron energy loss spectroscopy. It is shown that in PECVD films only around 30% of the Si excess agglomerates in clusters while an almost complete agglomeration occurs in sputtered films. These data are explained on the basis of the different initial structural properties of the as-deposited films that become crucial for the subsequent evolution. [ABSTRACT FROM AUTHOR]

The structural and optical properties of Si-rich silicon oxide (SRSO) layers obtained by plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering is examined. The studies have shown that in PECVD films only around 30% of the Si excess agglomerates in clusters while an almost complete agglomeration has occurred in sputtered films.