Abstract
In0.53Ga0.47As based capacitors and self-aligned transistors fabricated with HfO2/Al2O3/Si gate stacks in a gate-first process flow show promising electrical properties. With in-situ and ex-situ characterization methods, we review systematically the physical and chemical properties of the whole multilayered stack. Especially, critical instabilities which may potentially limit the achievement of sub-nanometer capacitance equivalent thickness and a low interface state density are described in detail. Finally we propose some alternative solutions to avoid the observed instability paths.