In this work the authors investigate La2O3 and ZrO2/La2O3 high-k gate dielectrics on p-type Ge metal-insulator-semiconductor capacitors. La2O3 on Ge exhibits good electrical properties in terms of interface states density, but it may not be scalable yielding high equivalent oxide thickness (EOT) after annealing. By depositing a thin (2 nm) La2O3 passivating layer followed by a ZrO2 cap, a gate stack is obtained which is a very good insulator with improved EOT, retaining at the same time the good passivating properties of La2O3. This indicates that the ZrO2/La2O3 combination could be scalable gate stack to be considered as a candidate for Ge metal-oxide-semiconductor devices. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3043533]