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O. Bethge, C. Henkel, S. Abermann, G. Pozzovivo, M. Stöger-Pollach, W.S.M. Werner, J. Smoliner, E. Bertagnolli:
"Stability of La₂O₃ and GeO₂ passivated Ge surfaces during ALD of ZrO₂ high-k dielectric";
Applied Surface Science, 258 (2012), 3444 - 3449.

La2O3 grown by atomic layer deposition (ALD) and thermally grown GeO2 are used to establish effective electrical surface passivations on n-type (1 0 0)-Ge substrates for high-k ZrO2 dielectrics, grown by ALD at 250 °C substrate temperature. The electrical characterization of MOS capacitors indicates an impact of the Ge-surface passivation on the interfacial trap density and the frequency dependent capacitance in the inversion regime. Lower interface trap densities can be obtained for GeO2 based passivation even though a chemical decomposition of the oxidation states occur during the ALD of ZrO2. As a consequence the formation of a ZrGeOx compound inside the ZrO2 matrix and a decline of the interfacial GeO2 are observed. The La2O3 passivation provides a stable amorphous lanthanum germanate phase at the Ge interface but also traces of Zr germanate are indicated by X-ray-Photoelectron-Spectroscopy and Transmission-Electron-Microscopy.

http://dx.doi.org/10.1016/j.apsusc.2011.11.094