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Dielectric Relaxation of La-Doped Zirconia Caused by Annealing Ambient

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ABSTRACT

La-doped zirconia films, deposited by ALD at 300°C, were found to be amorphous with dielectric constants (k-values) up to 19. A tetragonal or cubic phase was induced by post-deposition annealing (PDA) at 900°C in both nitrogen and air. Higher k-values (~32) were measured following PDA in air, but not after PDA in nitrogen. However, a significant dielectric relaxation was observed in the air-annealed film, and this is attributed to the formation of nano-crystallites. The relaxation behavior was modeled using the Curie–von Schweidler (CS) and Havriliak–Negami (HN) relationships. The k-value of the as-deposited films clearly shows a mixed CS and HN dependence on frequency. The CS dependence vanished after annealing in air, while the HN dependence disappeared after annealing in nitrogen.

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The relationship between leakage current density (Jg) and electric field (Eox) applied across the La0.35Zr0.65O2/IL (IL stands for interfacial layer) stacks for as-deposited and PDA samples. Break-down voltages (VBD) were indicated.
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Figure 5: The relationship between leakage current density (Jg) and electric field (Eox) applied across the La0.35Zr0.65O2/IL (IL stands for interfacial layer) stacks for as-deposited and PDA samples. Break-down voltages (VBD) were indicated.

Mentions: The leakage current characteristics of the La-doped films were evaluated from the I–V measurements, as shown in Figure 5. At low oxide fields (Eox at 0 to +2MV/cm), the leakage current density is improved under positive gate biases after annealing, which is attributed to the thicker IL. However, PDA also causes crystallization that introduces leakage current paths and reduces the break-down voltage. The leakage current densities at +2MV/cm are 1.6 × 10-5 Acm-2 for as-deposited samples, but below 5 × 10-8 Acm-2 after the 900°C PDA either in N2 or in air. This suggests that the effect of leakage currents on frequency dispersion is negligible during C–V measurements.


Dielectric Relaxation of La-Doped Zirconia Caused by Annealing Ambient
The relationship between leakage current density (Jg) and electric field (Eox) applied across the La0.35Zr0.65O2/IL (IL stands for interfacial layer) stacks for as-deposited and PDA samples. Break-down voltages (VBD) were indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211993&req=5

Figure 5: The relationship between leakage current density (Jg) and electric field (Eox) applied across the La0.35Zr0.65O2/IL (IL stands for interfacial layer) stacks for as-deposited and PDA samples. Break-down voltages (VBD) were indicated.
Mentions: The leakage current characteristics of the La-doped films were evaluated from the I–V measurements, as shown in Figure 5. At low oxide fields (Eox at 0 to +2MV/cm), the leakage current density is improved under positive gate biases after annealing, which is attributed to the thicker IL. However, PDA also causes crystallization that introduces leakage current paths and reduces the break-down voltage. The leakage current densities at +2MV/cm are 1.6 × 10-5 Acm-2 for as-deposited samples, but below 5 × 10-8 Acm-2 after the 900°C PDA either in N2 or in air. This suggests that the effect of leakage currents on frequency dispersion is negligible during C–V measurements.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

La-doped zirconia films, deposited by ALD at 300°C, were found to be amorphous with dielectric constants (k-values) up to 19. A tetragonal or cubic phase was induced by post-deposition annealing (PDA) at 900°C in both nitrogen and air. Higher k-values (~32) were measured following PDA in air, but not after PDA in nitrogen. However, a significant dielectric relaxation was observed in the air-annealed film, and this is attributed to the formation of nano-crystallites. The relaxation behavior was modeled using the Curie–von Schweidler (CS) and Havriliak–Negami (HN) relationships. The k-value of the as-deposited films clearly shows a mixed CS and HN dependence on frequency. The CS dependence vanished after annealing in air, while the HN dependence disappeared after annealing in nitrogen.

No MeSH data available.


Related in: MedlinePlus