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Title: Ge nanocrystals in lanthanide-based Lu2O3 high-k dielectric for nonvolatile memory applications
Authors: Seng, H. L.
Ho, V.
Chan, Mei Yin
Lee, Pooi See
Keywords: DRNTU::Engineering::Materials
Issue Date: 2007
Source: Chan, M. Y., Lee, P. S., Ho, V., & Seng, H. L. (2007). Ge nanocrystals in lanthanide-based Lu2O3 high-k dielectric for nonvolatile memory applications. Journal of applied physics, 102(9).
Series/Report no.: Journal of applied physics
Abstract: Ge nanocrystals embedded in lanthanide-based high-k dielectric (amorphous Lu2O3 in this work) were formed using pulsed laser deposition followed by rapid thermal annealing in N2 ambient. The formation and evolution of the Ge nanocrystals have been studied using transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) in conjunction with depth profiling, and secondary ion mass spectroscopy (SIMS) analysis. Plan-view TEM images indicated that the formation of nanocrystals was first initiated during the deposition process. The annealing treatment significantly enhanced the nucleation of Ge nanocrystals, resulting in a high areal density of 7 x10^11 cm−2 Ge nanocrystals with a mean size of about 6 nm in diameter in the amorphous Lu2O3 matrix. XPS depth profile analysis revealed that Ge nanocrystals were predominantly formed from the precipitation of Ge nuclei from the oxide phase. A low annealing temperature of 400 °C was sufficient to dissociate the GeO2 and GeOx leading to the formation of Ge nanocrystals. An accumulation of Ge species close to the upper Ge/Lu2O3 interface was observed from XPS and SIMS depth profile analysis. Different charge storage behaviors observed from the memory capacitor devices before and after annealing could be correlated to the changes in structure and composition of the film. The memory capacitor device fabricated from the annealed sample showed efficient charge storage effect under a low operation voltage without significant initial charge decay.
Rights: © 2007 American Institute of Physics. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The paper can be found at the following official URL: One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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