Band Alignment, Thermal Transport Property, and Electrical Performance of High-Quality β-Ga₂O₃/AlN Schottky Barrier Diode Grown via MOCVD

β-phase gallium oxide (β-Ga₂O₃)/aluminum nitride (AlN) heterojunctions hold significant potential for high-power and microwave device applications. In this study, we systematically investigated the properties of the β-Ga₂O₃/AlN heterostructure grown via metal-organic chemical vapor deposition (MOCVD). High-resolution X-ray diffraction (HRXRD) and Raman spectroscopy revealed the crystal structures and demonstrated the high-crystalline quality of both films. Atomic force microscopy (AFM) scans displayed a smooth β-Ga₂O₃ surface with a root-mean-square (RMS) roughness of 3.6 nm. Scanning electron microscopy (SEM) images showed a flat surface with distinct heterostructure boundaries. Elemental distributions across the interface were mapped by using energy-dispersive spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) analysis characterized the chemical components of the sample and confirmed a type-II band alignment in the heterojunction, which facilitates electron accumulation. Furthermore, the thermal conductivity of β-Ga₂O₃ was measured at 4.2 W/(m·K), and the thermal boundary conductivity at the β-Ga₂O₃/AlN interface was determined to be 118.6 MW/(m²·K) using the time-domain thermoreflectance (TDTR) method. Temperature-dependent electrical performance of the β-Ga₂O₃/AlN SBD, including a low turn-on voltage of 0.1 V, ideality factor of 4.22, modified Richardson constant of 48.5 A/cm² K², and high breakdown voltage of 1260 V, was obtained. All of these values are competitive among β-Ga₂O₃-based heterostructures. The findings highlight the excellent interface quality, superior heat dissipation capability, and decent SBD performance of the β-Ga₂O₃/AlN integration, offering a promising platform for developing β-Ga₂O₃-based power devices capable of operating at high temperatures.