Chemical nature of the passivation layer depending on the oxidizing agent in Gd2O3/GeO2/Ge stacks grown by molecular beam deposition
✍ Scribed by A. Lamperti; S. Baldovino; A. Molle; M. Fanciulli
- Book ID
- 104052765
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 620 KB
- Volume
- 88
- Category
- Article
- ISSN
- 0167-9317
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✦ Synopsis
In Ge-based metal oxide semiconductor technology, the insertion of a passivation layer seems to be crucial in unpinning the Fermi level at the interface and in reducing the amount of interface defects. GeO 2 was obtained by atomic oxygen (AO), molecular oxygen or ozone chemisorption. Atomic or molecular oxygen was used in the deposition of Gd 2 O 3 . Gd 2 O 3 thin films were grown by molecular beam deposition directly on (1 0 0) Ge or on a GeO 2 interlayer. The chemical nature of the Gd 2 O 3 /Ge interface was characterized by time-of-flight secondary ion mass spectrometry depth profiles. Without GeO 2 layer Gd and Ge interdiffusion is observed and the concomitant formation of GeAOAGd bonds is also supported by X-ray photoelectron spectroscopy energy shift at the Ge 3d peak and by a singularity in the interface defect energy distribution at $0.48 eV. Further, depending on the GeO 2 formation process, the profile shape of Ge and O related secondary ions at the GeO 2 /Ge interface can be related with a defective Ge region close to the GeO 2 /Ge. In particular, considering the ratio between Ge and GeO 2 related secondary ion signals, the interlayer passivated using AO turns out to be comparatively enriched in Ge, while the use of ozone for GeO 2 formation leads to a Ge deficient layer.