Investigation of Rare Earth (RE = La, Dy, and Er) doping of HfO2 by perturbed angular correlation spectroscopy
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2016
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FABIO HENRIQUE DE MORAES CAVALCANTE
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INTERNATIONAL CONFERENCE ON HYPERFINE INTERACTIONS AND THEIR APPLICATIONS
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Resumo
The hyperfine interactions at 181Hf(181Ta) probe nuclei in HfO2 samples doped with 5%
rare-earth (RE = La, Dy, and Er) elements were measured by perturbed angular correlation
(PAC) spectroscopy. Hafnium dioxide has been extensively studied as a potential alternative
to silicon dioxide as dielectric gate material in the silicon based
complementary-metal-oxide-semiconductors (CMOS) technology due to its high dielectric
constant and relatively high thermal stability with respect to silicon. The addition of RE to
HfO2 can suppress oxygen vacancies and promote a change in the crystal structure
increasing the dielectric permitivity. Samples were prepared using the sol-gel chemical
method, starting from very pure metals. The resulting powder of each sample was annealed
in air at 550 o C for 12 h. The crystal structures of samples were checked by X-ray
diffraction. Result revealed only a single phase corresponding to the monoclinic phase P
21/C of HfO2 for all samples. PAC spectra measured at room temperature were fitted with
two electric quadrupole interactions with different environments for all samples including a
pure HfO2. The major components (70-75%) were characterized by quadrupole
frequencies 𝜈𝑄 ∼ 790 MHz with a distribution around 6% and asymmetry parameter 𝜂 =
0.34 for Dy- and Er-doped samples. La-doped sample showed a slightly lower frequency
(𝜈𝑄 = 727 MHz) with larger asymmetry parameter (𝜂 = 0.43) for the major component.
The major components are ascribed to probe nuclei at regular monoclinic sites of HfO2. The
quadrupole frequency 𝜈𝑄 and asymmetry parameter 𝜂 for Dy- and Er-doped samples
agree well with those values reported in the literature [1]. The minor components were
characterized by 𝜈𝑄 ∼ 760 MHz with a distribution around 8% and asymmetry parameter
𝜂 = 0.75 for Dy- and Er-doped samples and 𝜈𝑄 = 783 MHz and 𝜂 = 0.61 for La-doped
HfO2. These values are quite different from those reported for pure sample [1], assigned to
probe nuclei near defects, and probably they are due to probe nuclei close to RE dopants,
which reduce the presence of defects.
Como referenciar
SALES, TATIANE; CAVALCANTE, FABIO; CABRERA-PASCA, GABRIEL; PEREIRA, LUCIANO F.; SAXENA, RAJENDRA; CARBONARI, ARTUR. Investigation of Rare Earth (RE = La, Dy, and Er) doping of HfO2 by perturbed angular correlation spectroscopy. In: TEMST, KRISTIAAN (ed.); VANTOMME, ANDRE (ed.); COTTENIER, STEFAAN (ed.); PEREIRA, LINO (ed.). In: INTERNATIONAL CONFERENCE ON HYPERFINE INTERACTIONS AND THEIR APPLICATIONS, July 3-8, 2016, Leuven, Belgium. Abstract... Leuven, Belgium: Instituut voor Kern- en Stralingsfysica, 2016. Disponível em: http://repositorio.ipen.br/handle/123456789/28007. Acesso em: 03 Nov 2026.
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