“…Among them, the GaAs-based MOS device has been considered as the most viable candidate due to its higher mobility, higher breakdown voltage, and larger band gap than Si [3]. Meanwhile, many high-k materials, e.g., HfO 2 [4], TiO 2 [5], La 2 O 3 [6], Y 2 O 3 [7], etc., have been introduced into GaAsbased MOS devices for the scaling down of the device dimension. However, since GaAs easily forms oxides of Ga and As that create interface defects and contain border traps, high interface-state density (D it ) at the interface of high-k/GaAs is generated, leading to the degradation of device performance [8].…”