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Nanostructured films consisting of single Si nanoparticles (NPs) and Er3+ ions layers separated by nanometer-scale Al2O3 layers of controlled thickness have been prepared in order to tune the energy transfer between Si NPs and Er3+ ions. The amorphous Si NPs with an effective diameter of ∼4.5 nm are formed during growth and are able to sensitize the Er3+ ions efficiently with no postannealing treatments. The characteristic distance for energy transfer from Si NPs to Er3+ ions in Al2O3 is found to be in the 1 nm range. It is shown that in the nanostructured films, it is possible to achieve an optimized configuration in which almost all the Er3+ ions have the potential to be excited by the Si NPs. This result stresses the importance of controlling the dopant distribution at the nanoscale to achieve improved device performance. [ABSTRACT FROM AUTHOR]

Er–Tm codoped a-Al2O3 thin films prepared by alternate pulsed laser deposition show a broad photoluminescence band with two characteristic peaks at 1540 and at 1640 nm, respectively, related to Er3+ and Tm3+ emissions. Two series of films have been prepared. For the first series, the Tm concentration [Tm] has been increased while keeping constant the Er concentration [Er]. The results show that the photoluminescence intensity at 1640 nm (I1640) to that at 1540 nm (I1540) decreases and that at 1640 nm (I1640) increases, i.e., the (I1640/I1540) ratio increases as [Tm] is increased. For [Tm]/[Er]=3, a fairly flat emission spectrum (I1640/I1540∼1) with a full width at half maximum of 230 nm is achieved. For the second series both [Tm] and [Er] are increased while keeping the [Tm]/[Er] ratio constant. The I1640/I1540 ratio tends to be constant with a full width at half maximum of 150 nm. The lifetime values decrease in all cases as [Tm] increases. The evolution of the I1640/I1540 and lifetimes as a function of [Tm] as well as the analysis of the latter considering Er as a donor and Tm as an acceptor evidence that there is an efficient energy transfer from Er3+ to Tm3+. These results suggest that enhanced performance with a flat broadband emission useful for planar integrated devices is achievable by further dopant engineering in the nanoscale. [ABSTRACT FROM AUTHOR]

Erbium doped Al[sub 2]O[sub 3] films with concentrations up to 6×10[sup 20] Er cm[sup -3] have been prepared in a single step process by pulsed-laser deposition. Alternate ablation of Al[sub 2]O[sub 3] and Er targets has been used to control the in-depth distribution and in-plane concentration of Er[sup 3+] ions independently. The characteristic Er[sup 3+] photoluminescence response at 1.53 μm has been studied as a function of the Er[sup 3+] distribution. It is found that lifetime values can be greatly increased by increasing the Er[sup 3+]–Er[sup 3+] in-depth separation above 3 nm. This result can be related to a reduced Er[sup 3+]–Er[sup 3+] energy migration process. The in-plane Er[sup 3+] concentration was increased by either increasing the number of pulses on the Er target or the laser energy density for ablation. By the latter method in-plane concentrations as high as 1.1×10[sup 14] Er cm[sup -2] per layer (corresponding to 2×10[sup 20] Er cm[sup -3]) were achieved, while keeping lifetime values as high as 6 ms. This result is explained in terms of shallow Er[sup 3+] implantation during deposition. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Provides information on a study that used of molecular beam epitaxy in the incorporation and optical activation of erbium in silicon to focus on the effect of oxygen on the erbium-related luminescence.

Presents a study that examined optical activation, excitation and concentration limits of erbium (Er) in crystal silicon (Si). Background on erbium doping of silicon; Factors required for attaining efficient luminescence from Er in Si.

Abstract: Alternate pulsed laser deposition from the host (Al2O3) and dopant (Er, Yb) targets has been used to prepare artificially nanostructured films in which the rare earth ion–ion separation is controlled in the nanometer scale in order to control energy transfer between ions. One series of films was prepared in the standard on-axis configuration, i.e. a static substrate being centred with respect to the plasma expansion axis. A second series of films was prepared by rotating the substrate with respect to a shifted axis parallel to the plasma expansion one (off-axis configuration). The latter configuration leads to films with enhanced thickness and Er related photoluminescence intensity uniformity. More interestingly, the Er related photoluminescence lifetime in as-grown films increases up to 2.5ms, which is much higher than the maximum value of 1ms obtained for the on-axis configuration films. This enhancement is discussed in terms of a decrease of defect density when using the off-axis configuration. [Copyright &y& Elsevier]

Describes how erbium (Er)-doped aluminum oxide films have been deposited in a single-step process by pulsed laser deposition using independent ablation of aluminum oxide and Er targets. Control of the Er[sup 3+] ions in-depth distribution; Characteristic Er[sup 3+] photoluminescence at 1.54 micrometer.

Thin Al2O3 films are grown and in situ doped with erbium by pulsed laser deposition in a single step process, by alternate ablation from Al2O3 and Er targets. The as-deposited films have an Er step dopant profile throughout the film thickness, whose concentration depends on the number of pulses at the Er target. The as-grown films are optically active, as evidenced by the photoluminescence spectrum centered at 1.533 μm, corresponding to intra-4f transitions in Er3+. The photoluminescence intensity increases upon annealing due to an increase of the luminescence lifetime. This is most likely a result of a decrease in the nonradiative decay channels, related to annealing of defects in the Al2O3 film. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a photoluminescence characterization of hydrogenated amorphous silicon doped with erbium by ion implantation. Temperature range used in thermal annealing; Mediation of erbium cations by photocarriers; Luminescence quenching factor in oxygen codoping.

Investigates the segregation and trapping of erbium during silicon (100) molecular beam epitaxy. Formation of silicide precipitates; Result of growing silicon in a certain oxygen background pressure; Absence of erbium segregation on silicon (111).

Abstract: Nanostructured Er3+–Si nanoparticles (NPs) codoped Al2O3 films were synthesized by a one step laser based deposition process which allows to form the Si NPs in situ at room temperature, and to control their size and separation with the Er ions in the nanoscale. Two different thermal annealing treatments are studied in order to optimize the photoluminescence (PL) emission: rapid thermal annealing (RTA) at 900°C during 2min, and conventional furnace step annealing at different temperatures up to 750°C for 1h. After RTA process the films show an important enhancement on the photoluminescence lifetime values which is related to a reduction of the non-radiative decay channels. Nevertheless, the Si NPs to Er ions energy transfer is strongly reduced. In contrast after conventional furnace annealing up to 700°C, although there is only a moderate increase of the photoluminescence lifetime values, the excitation of Er ions through Si NPs is still active and as a consequence a large enhancement of the photoluminescence intensity with respect to the Er-only doped film is achieved. These different behaviours are most likely related to structural and chemical changes in the Er environment upon the different annealing processes. [Copyright &y& Elsevier]

We report the preparation and optical performance of thin films produced by pulsed laser deposition in vacuum at room temperature, by focusing an ArF excimer laser onto two separate targets: a commercial ceramic SiAlON and a metallic Er target. As a result of the alternate deposition Er:SiAlON films were formed. The as grown films exhibited an Er-related emission peaking at 1532 nm. The role of the PLD energy density during deposition on the final matrix film was investigated, in order to achieve an optimized matrix composition with enhanced optical properties, and its effect on the light emission performance. [ABSTRACT FROM AUTHOR]