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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.

No MeSH data available.


(a) C–V results at different frequencies from the air-annealed sample. Significant frequency dispersion was observed. (b) No frequency dispersion in C–V measurements was observed in the thermal oxide (SiO2) sample with the back-side contact prepared in the same way as for the LaZrO sample shown in (a).
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Figure 4: (a) C–V results at different frequencies from the air-annealed sample. Significant frequency dispersion was observed. (b) No frequency dispersion in C–V measurements was observed in the thermal oxide (SiO2) sample with the back-side contact prepared in the same way as for the LaZrO sample shown in (a).

Mentions: Before discussing the k-value increase, the causes of frequency dispersion must be totally understood. Figure 4 (a) indicates that a large frequency dispersion was observed during C–V measurements in the air-annealed sample. There are five reasons that may cause the frequency dispersion observed: (1) series resistances, (2) parasitic effects (including back contact imperfection and cables and connections), (3) leakage currents, (4) the interlayer between La0.35Zr0.65O2 layer and semiconductor silicon substrate, or (5) a k-value dependence on frequency of the La0.35Zr0.65O2 dielectric. To obtain the genuine intrinsic properties and permittivity of the La0.35Zr0.65O2 dielectric from the CV measurements, the first four effects must be eliminated.


Dielectric Relaxation of La-Doped Zirconia Caused by Annealing Ambient
(a) C–V results at different frequencies from the air-annealed sample. Significant frequency dispersion was observed. (b) No frequency dispersion in C–V measurements was observed in the thermal oxide (SiO2) sample with the back-side contact prepared in the same way as for the LaZrO sample shown in (a).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211993&req=5

Figure 4: (a) C–V results at different frequencies from the air-annealed sample. Significant frequency dispersion was observed. (b) No frequency dispersion in C–V measurements was observed in the thermal oxide (SiO2) sample with the back-side contact prepared in the same way as for the LaZrO sample shown in (a).
Mentions: Before discussing the k-value increase, the causes of frequency dispersion must be totally understood. Figure 4 (a) indicates that a large frequency dispersion was observed during C–V measurements in the air-annealed sample. There are five reasons that may cause the frequency dispersion observed: (1) series resistances, (2) parasitic effects (including back contact imperfection and cables and connections), (3) leakage currents, (4) the interlayer between La0.35Zr0.65O2 layer and semiconductor silicon substrate, or (5) a k-value dependence on frequency of the La0.35Zr0.65O2 dielectric. To obtain the genuine intrinsic properties and permittivity of the La0.35Zr0.65O2 dielectric from the CV measurements, the first four effects must be eliminated.

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.