Characterization of high-κ LaLuO₃ thin film grown on AlGaN/GaN heterostructure by molecular beam deposition

We report the study of high-dielectric-constant (high-) dielectric LaLuO₃ (LLO) thin film that is grown on AlGaN/GaN heterostructure by molecular beam deposition (MBD). The physical properties of LLO on AlGaN/GaN heterostrucure have been investigated with atomic force microscopy, x-ray photoelectron spectroscopy, and TEM. It is revealed that the MBD-grown 16 nm-thick LLO film is polycrystalline with a thin (∼2 nm) amorphous transition layer at the LLO/GaN interface. The bandgap of LLO is derived as 5.3 0.04 eV from O1s energy loss spectrum. Capacitance-voltage (C-V) characteristics of a Ni-Au/LLO/III-nitride metal-insulator-semiconductor diode exhibit small frequency dispersion (2) and reveal a high effective dielectric constant of ∼28 for the LLO film. The LLO layer is shown to be effective in suppressing the reverse and forward leakage current in the MIS diode. In particular, the MIS diode forward current is reduced by 7 orders of magnitude at a forward bias of 1 V compared to a conventional Ni-Au/III-nitride Schottky diode.