Morphological Evolution of Atomic Layer Deposited Hafnium Oxide on Aligned Carbon Nanotube Arrays.
basic_science · Level V
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- Record sourced from PubMed, PMID 39347618.
- Also identified by DOI 10.1021/acs.nanolett.4c03407.
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Abstract
Microscopic study of the nucleation and growth of atomic layer deposition (ALD) dielectrics onto carbon nanotubes (CNTs) is an essential while challenging task toward high-performance devices. Here, we capture the morphological evolution and growth behaviors of ALD-HfO<sub>2</sub> onto SiO<sub>2</sub>/Si-supported aligned CNT arrays (A-CNTs) under three ALD recipes via cross-sectional high-resolution scanning transmission electron microscopy. The HfO<sub>2</sub> in ALD I (200 °C) preferentially nucleates on the SiO<sub>2</sub> substrate in heterogeneous growth mode, resulting in films with considerable pinholes, while ALD II (90 °C) and III (90 °C and extra H<sub>2</sub>O presoak) exhibit homogeneous growth with nucleation on both SiO<sub>2</sub> and CNTs, yielding uniform films. Arrangement defects in A-CNTs exacerbate nonuniformity of HfO<sub>2</sub> and tube-tube separation plays deterministic roles affecting the HfO<sub>2</sub>-CNT interfacial morphology. Electrical measurements from A-CNTs metaloxide-semiconductor devices validate these findings. Our investigation contributes valuable insights for optimizing ALD processes for enhanced dielectric integration on A-CNTs in next-generation electronics.