Fernando Claudio Zawislak

Cluster coarsening and luminescence emission intensity of Ge nanoclusters in SiO2 layers

SiO2 layers 180 nm thick are implanted with 120u200akeVu200aGe+ ions at a fluence of 1.2×1016u200acm−2. The distribution and coarsening evolution of Ge nanoclusters are characterized by Rutherford backscattering spectrometry and transmission electron microscopy and the results are correlated with photoluminescence measurements as a function of the annealing temperatures in the 400u200a°C⩽T⩽900u200a°C range. At 400u200a°C we observe a monomodal array of clusters characterized by a mean diameter 〈φ〉=2.2 nm which increases to 〈φ〉=5.6 nm at 900u200a°C. This coarsening evolution occurs concomitantly with a small change of the total cluster–matrix interface area and an increase of the Ge content trapped in observable nanoclusters. However, at 900u200a°C a significant fraction of up to about 20% of the Ge content still remains distributed in the matrix around the nanoparticles. The results are discussed in terms of possible atomic mechanisms involved in the coarsening behavior that lead to the formation of the oxygen deficiency luminescence ce...

Mass and energy dependence of implanted ion profiles in the AZ111 photoresist

Profiles of Bi, Xe, Sn, Kr, Ga, Fe, K, Ar, P, Na, and F implanted into the AZ111 photoresist are compared with recent theoretical predictions. With the exception of the noble gases and F, the experimental results are well fitted by the Biersack–Haggmark [Nucl. Instrum. Methods 174, 257 (1980)] Monte Carlo calculations. For the noble gases we obtain ranges up to a factor of 2 shorter than the above predictions. Fluor changes the profile as function of energy, being nearly Gaussian at 30 keV and distributing according to the calculated ionization at 70 keV.

Effect of annealing atmosphere on the structure and luminescence of Sn-implanted SiO2 layers

Sn nanoclusters are synthesized in 180 nm SiO2 layers after ion implantation and heat treatment. Annealings in N2 ambient at high temperatures (T⩾700°C) lead to the formation of Sn nanoclusters of different sizes in metallic and in oxidized phases. High-resolution transmission electron microscopy (TEM) analyses revealed that the formed larger nanoparticles are composed by a Sn metallic core and a SnOx shell. The corresponding blue-violet photoluminescence (PL) presents low intensity. However, for heat treatments in vacuum, the PL intensity is increased by a factor of 5 and the TEM data show a homogeneous size distribution of Sn nanoclusters. The low intensity of PL for the N2 annealed samples is associated with Sn oxidation.

Range measurements and thermal stability study of AZ111 photoresist implanted with Bi ions

The Rutherford backscattering technique has been used to determine the range parameters of Bi ions implanted into AZ111 photoresist film at energies from 10 to 400 keV. An overall good agreement is found between the experimental results and the theoretical predictions by Biersack, Ziegler, and Littmark. It is also observed that a variation in the implantation dose does not affect the projected range and range straggling results, despite the fact that chemical modification of the implanted polymer layer is detected. In addition, we find that a shallow implantation of the polymer film with Bi ions increases the temperature at which the photoresist starts to decompose. Finally, at 300u2009°C the implanted Bi atoms diffuse preferentially toward the bulk. For this temperature, two different diffusion coefficients are estimated, one for the damaged region Dd=1.2×10−5 cm2/s and another for the bulk Db=1.2×10−14 cm2/s.

Aging effects on the nucleation of Pb nanoparticles in silica

The ion beam synthesis of Pb nanoparticles (NPs) in silica is studied in terms of a two step thermal annealing process consisting of a low temperature long time aging treatment followed by a high temperature short time one. The samples are investigated by Rutherford backscattering spectrometry and transmission electron microscopy. The results obtained show that highly stable Pb trapping structures are formed during the aging treatment. These structures only dissociate at high temperatures, inhibiting the nucleation of NPs in the metallic phase and causing an atomic redistribution that renders the exclusive formation of a two dimensional, uniform and dense array of Pb NPs at the silica–silicon interface. The results are discussed on the basis of classic thermodynamic concepts.

Low temperature diffusion study of Xe implanted into a photoresist film

Abstract We report on low temperature diffusion results of Xe implanted at 90 K into a AZ1350 photoresist. The as implanted Xe spectrum shows a regular profile with range parameters well reproduced by the theory. Successive annealings performed in the temperature range 90–293 K reveal the existence of two diffusional processes. A slow one which occurs in the near surface region and a rapid one (in the deeper zone) which is responsible for the apperance of a penetrating tail directed toward the bulk.

Diffusion of Hf in α-Zr

The diffusion of Hf in α-Zr has been studied in the temperature range 773–1115 K for the first time using the Rutherford backscattering technique. For this purpose we have used 250 Å thick Hf films, which were deposited on two types of Zr samples. Our results show that in both cases, the diffusion coefficients follow curved Arrhenius plots. For the pure Zr material the diffusion coefficients are systematically lower than for Zr samples of lower purity. These results indicate that the Hf diffusion mechanism is at least partially of extrinsic character. Finally it should be mentioned that the present data lie significatively below the values of self-diffusion in α-Zr.

Low temperature aging effects on the formation of Sn nanoclusters in SiO2∕Si films and interfaces

The formation of Sn nanocrystals (NCs) in ion implanted SiO2∕Si films is investigated using Rutherford backscattering spectrometry and transmission electron microscopy. Low temperature and long time aging treatments followed by high temperature thermal annealings lead to the formation of a dense bidimensional NC array located at the SiO2∕Si interface. This behavior is discussed considering the formation of small Sn clusters with a significantly improved thermal stability. The present experimental results are in good agreement with recent theoretical predictions that small Sn clusters can have their melting temperature enhanced in more than 1000°C.

Formation of epitaxial β-Sn islands at the interface of SiO2∕Si layers implanted with Sn ions

180 nm SiO2 layers on Si (100) were implanted with Sn ions producing a profile with a peak concentration of 3 at.u2009% at the middle of the oxide. After high temperature (900–1100u2009°C) annealing, an array of β-Sn islands epitaxially attached to the Si was observed at the SiO2∕Si(100) interface due to the migration of the implanted Sn atoms. The breakdown of the planar SiO2∕Si interface and the appearance of the island system is discussed in terms of the Sn–Si equilibrium properties. Our results reveal a new method to create a high density of nanosized islands with good uniformity in size and shape.

Radiation induced diffusion of Xe implanted into the AZ1350 polymer

Abstract The present work shows that Xe ions partially diffuse during or after room temperature implantation into the AZ1350 photoresist. Isothermal annealing performed at room temperature shows that this diffusional process is not of thermal origin. These experiments suggest that the Xe diffusion is a self-radiation induced process. In order to explore this hypothesis we have Ar-postbombarded the Xe implanted samples at a fixed energy and in a wide range of fluences. The results clearly indicate the existence of a radiation induced diffusion process via a trapping-detrapping mechanism. The trapping probability is proportional to the Xe implantation fluence and the detrapping is proportional to the Ar irradiation fluence, A final postirradiation experiment performed with Xe atoms indicates that the nuclear stopping energy transfer plays an important role in the radiation induced diffusion mechanism.