I. Introduction
Recently III–V metal–oxide–semiconductor field-effect transistors (MOSFETs) have been widely investigated for post CMOS application because of the high electron mobility nature of III–V materials. Unlike on Si substrate, the lack of high-quality thermodynamically stable gate dielectric insulators on III–V compound semiconductors is still the main obstacle to realize the III–V MOSFET technology with commercial value. and are the most effective high- oxides that were used as gate insulators for III–V metal–oxide–semiconductor (MOS) devices [1]–[3]. However, the integration of novel high-k oxides on III–V compound semiconductors as gate insulators still needs a lot of effort. Rare earth oxide (REO) thin films are currently being investigated as high-k gate dielectric for future ultrascaled devices, due to their high dielectric constant and high conduction-band offset with respect to silicon [4]–[7]. Among the binary REOs, is considered as one of the most potential gate dielectric materials due to its promising properties, such as high- value of (20–27), high bandgap of 4.6 eV, and high conduction-band offset of 23 eV.