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ElectroComponent Science and Technology
Volume 6 (1980), Issue 3-4, Pages 219-222

Thin Film Al-Al2O3-Al Capacitors With Dielectric Layer Formed at 400℃

Technical University, Wrocław, Poland

Received 30 June 1979

Copyright © 1980 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A comparative study is made of Al2O3 layers formed at 400℃ in molten KNO3 and Al2O3 formed at room temperature in a common solution of ammonium pentaborate in ethylene glycol. At 400℃ and constant current (0.5 mA/cm2 ) the linear anodization range is limited to 2.7 V by scintillation and local oxide breakdowns. Nonporous 200 Å thick (0.4 μF/cm2) oxide layers were produced at 2.0 V (400℃) and 8 V (20℃). Electron diffraction indicated a γ-Al2O3 structure at an anodization temperature of 400℃ and amorphous structure at room anodization temp. The initial values of tan δ were 100·104±40·104 and 400·104±200·104 respectively.

Capacitance and tan δ measurements during accelerated life test indicated that the films produced at 400℃ are not superior to those formed at room temperature. In both cases a diffusion of metal at the metal-oxide interface seems to be the main ageing mechanism.

The internal electrical field measured by the C-V method was unchanged in γ-Al2O3 layers during the life test.