A. Carnera

Bio: A. Carnera is an academic researcher from Central University of Tamil Nadu. The author has contributed to research in topics: Ion implantation & Silicon. The author has an hindex of 17, co-authored 49 publications receiving 836 citations.

Structural characterization of proton exchanged LiNbO3 optical waveguides

Abstract: This paper reports the results of structural analysis of proton‐exchanged lithium niobate optical waveguides fabricated in Z‐, X‐, and Y‐cut substrates immersed in pure benzoic acid Rutherford backscattering spectrometry, nuclear reactions, secondary ion mass spectrometry, scanning electron microscopy, and x‐ray diffraction were used to measure atomic composition profiles and the marked lattice distortion induced by the proton exchange process in the waveguiding layer H and Li concentration measurements indicate an exchange of about 70% of the Li atoms are present in the virgin LiNbO3 crystal

Optimal crystal surface for efficient channeling in the new generation of hadron machines

Abstract: The new generation of hadron machines may profitably take advantage of channeling for steering and collimation of high-energy particle beams. In that case, the requirements on the quality of the crystal surface are rather stringent in terms of both lattice perfection and roughness. Here, the authors show the structural and morphological characterizations of crystals fabricated through a method to achieve a surface that fulfills all needed specifications for application in hadron machines.

Role of fluorine in suppressing boron transient enhanced diffusion in preamorphized Si

Abstract: We have explained the role of fluorine in the reduction of the self-interstitial population in a preamorphized Si layer under thermal treatment. For this purpose, we have employed a B spike layer grown by molecular-beam epitaxy as a marker for the self-interstitial local concentration. The amorphized samples were implanted with 7×1012, 7×1013, or 4×1014 F/cm2 at 100 keV, and afterwards recrystallized by solid phase epitaxy. Thermal anneals at 750 or 850 °C were performed in order to induce the release of self-interstitials from the end-of-range (EOR) defects and thus provoke the transient enhanced diffusion of B atoms. We have shown that the incorporation of F reduces the B enhanced diffusion in a controlled way, up to its complete suppression. It is seen that no direct interaction between B and F occurs, whereas the suppression of B enhanced diffusion is related to the F ability in reducing the excess of silicon self-interstitials emitted by the EOR source. These results are reported and discussed.

TiO2, LiNb3O8, and (TixNb1−x)O2 compound kinetics during Ti:LiNbO3 waveguide fabrication in the presence of water vapors

Abstract: The presence of water vapor in the annealing atmosphere during Ti:LiNbO3 optical waveguide fabrication prevents Li out‐diffusion, inhibits LiNb3O8 growth, and furthermore decomposes this phase if already formed. As a consequence, the TiO2 and the mixed oxide (TixNb1−x)O2 growth kinetics change. A proton in‐diffusion in LiNbO3 with OH− defects and (Li1−yHy)NbO3 molecule formation is suggested to explain these effects and to account for the detected increase of absorbance at 3480 cm−1.

Negative thermal expansion materials

Abstract: The ZrW2O8 family of materials has been shown to exhibit the unusual property of negative thermal expansion over a wide temperature range α-ZrW2O8 itself shows negative thermal expansion from 2 K to 1443 K with a coefficient of thermal expansion α1 of -91×10-6 K-1 between 2 and 300 K This behaviour can be related to the unusual structure of these materials, which possess a family of low energy phonon modes with negative Gruneisen parameters α-ZrW2O8 also shows a phase transition at 448 K to β-ZrW2O8 in which oxygen atoms are dynamically disordered These phenomena have been investigated by a number of techniques Results of powder neutron diffraction at 260 different temperatures are presented

Wavelength dispersion of Ti induced refractive index change in LiNbO 3 as a function of diffusion parameters

Abstract: Z -cut X -propagating, LiNbO 3 :Ti planar waveguides have been characterized over a wide range of diffusion conditions. Measurements of Ti concentration and refractive indexes have revealed Gaussian profiles. Their dependence with diffusion conditions have been studied. The relation, established at several wavelengths ( \lambda = 0.6328 \mu m, 1.1523 μm, 1.523 μm), between extraordinary and ordinary refractive index change \Deltan_{e,0}(z) and titanium concentration C(z) is found to be nonlinear and of the form: \Deltan_{e,0}(z) = A_{e,0}(C_{0},\lambda) (C(z))^{\alpha_{e,0}} While \alpha_{e,0} is a constant, the proportionality coefficient A_{e,0} depends not only on the wavelength λ, but also on the diffusion conditions, characterized by C 0 , the Ti surface concentration of the diffused guide. Such a nonlinearity of Ti diffusion in LiNbO 3 has been revealed thanks to a complete and wide range investigation on both indiffused Ti and index profiles.