Browsing by Author "Barradas, N P"

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    In situ study of the growth properties of Ni-rare earth silicides for interlayer and alloy systems on Si(100)
    (2012) Demeulemeester, J; Knaepen, W; Smeets, D; Schrauwen, A; Comrie, C M; Barradas, N P; Vieira, A; Detavernier, C; Temst, K; Vantomme, A
    We report on the solid-phase reaction of thin Ni-rare earth films on a Si(100) substrate, for a variety of rare earth (RE) elements (Y, Gd, Dy, and Er). Both interlayer (Ni/RE/〈Si〉) and alloy (Ni-RE/〈Si〉) configurations were studied. The phase sequence during reaction was revealed using real-time x-ray diffraction whereas the elemental diffusion and growth kinetics were examined by real-time Rutherford backscattering spectrometry. All RE elements studied exert a similar influence on the solid phase reaction. Independent of the RE element or its initial distribution a ternary Ni 2Si2 RE phase forms, which ends up at the surface after NiSi growth. With respect to growth kinetics, the RE metal addition hampers the Ni diffusion process even for low concentrations of 2.5 at. %, resulting in the simultaneous growth of Ni-rich silicide and NiSi. Moreover, the formation of Ni 2Si2 RE during NiSi growth alters the Ni diffusion mechanism in the interlayer causing a sudden acceleration of the Ni silicide growth. Besides a significant effect on the silicide growth, we have found that adding 5 at. % Er (relative to Ni) lowers the NiSi Schottky barrier height on n-type Si(100) by approximately 0.1 eV for the interlayer and alloy configuration.
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    On the growth kinetics of Ni(Pt) silicide thin films
    (2013) Demeulemeester, J; Smeets, D; Comrie, C M; Barradas, N P; Vieira, A; Van Bockstael, C; Detavernier, C; Temst, K; Vantomme, A
    We report on the effect of Pt on the growth kinetics of δ-Ni2Si and Ni 1−xPtxSi thin films formed by solid phase reaction of a Ni(Pt) alloyed thin film on Si(100). The study was performed by real-time Rutherford backscattering spectrometry examining the silicide growth rates for initial Pt concentrations of 0, 1, 3, 7, and 10 at. % relative to the Ni content. Pt was found to exert a drastic effect on the growth kinetics of both phases. δ-Ni2Si growth is slowed down tremendously, which results in the simultaneous growth of this phase with Ni 1−xPtxSi. Activation energies extracted for the Ni 1−xPtxSi growth process exhibit an increase from Ea = 1.35 ± 0.06 eV for binary NiSi to Ea = 2.7 ± 0.2 eV for Ni 1−xPtxSi with an initial Pt concentration of 3 at. %. Further increasing the Pt content to 10 at. % merely increases the activation energy for Ni 1−xPtxSi growth to Ea = 3.1 ± 0.5 eV.