Integration of high-dielectric constant Ta_2O_5 oxides on diamond for power devices

摘要

The authors report on the direct integration or high-dielectnc constant (high-k) Ta_2O_5 films on p-type single crystal diamond for high-power electronic devices. Crystallized hexagonal phase δ-Ta_2O_5 film is achieved on diamond by annealing the amorphous Ta_2O_5 film deposited by a sputter-deposition technique. The electrical properties of the Ta_2O_5 thin films are investigated by fabricating metal-insulator-semiconductor (MIS) diodes. The leakage current of the MIS diode is as low as 10～8 A/cm2 for the as-deposited amorphous Ta_2O_5 film and 10~(-2) A/cm~2 for the crystallized film, which is 108 and 102 times lower than that of the Schottky diode at a forward bias of -3 V, respectively. The dielectric constant of the amorphous Ta_2O_5 films is measured to be 16 and increases to 29 after annealing at 800 ℃. Different current leakage mechanisms and charge trapping behaviors are proposed for the amorphous and crystallized Ta_2O_5 thin films.