The invention provides a high-k
gate dielectric composite material, a preparation method thereof and a beta-Ga2O3 MOS (
Metal Oxide Semiconductor) power device. The
composite material comprises a beta-Ga2O3 substrate; the SiO2 interface buffer layer is formed on at least one surface of the beta-Ga2O3 substrate; the Al2O3
transition layer is formed on the surface of the SiO2 interface buffer layer; the AlON
interface layer is formed on the surface of the Al2O3
transition layer; and the HfO2 high-k main
dielectric layer is formed on the surface of the AlON
interface layer. Experimental results show that the
composite material provided by the invention has a
dielectric constant of 15-30, a forbidden bandwidth of greater than 5eV, an interface
state density of less than 1 * 10 < 12 > cm <-2 > eV <-1 > and a breakdown
field strength of 7MV / cm-15MV / cm, can effectively improve the interface characteristics of a beta-Ga2O3 MOS power device when being used for the beta-Ga2O3 MOS power device, improves the reliability of a gate medium, and is suitable for being applied to high-
voltage and high-temperature power devices.