Temperature-Dependent Electrical and Interfacial Properties of LaB6/H-Terminated Diamond Schottky Barrier Diodes

Hydrogen-terminated diamond (H-diamond) has attracted extensive attention because of its unique surface electronic structure, particularly its negative electron affinity surface and surface transfer doping effect. However, in H-diamond Schottky barrier diodes (SBDs), the interface states at the Schottky interface can strongly influence device characteristics. Therefore, clarifying the evolution of interface states under thermal conditions is essential for understanding carrier transport and thermally activated interfacial behavior. In this work, the temperature-dependent interfacial characteristics of H-diamond SBDs with a LaB6 interlayer were systematically investigated over the temperature range of 300–500 K. Temperature-dependent capacitance-voltage (C–V) and current-voltage (I–V) measurements were used to obtain the Schottky barrier height, ideality factor, and acceptor concentration. The interface state density (Dit) was then derived from the bias-dependent ideality factor. The results reveal that Dit is on the order of 1013 cm–2 eV–1, in the energy range of approximately 0.1–0.37 eV above the valence band edge, and exhibits a clear decreasing trend as temperature increases. In addition, X-ray photoelectron spectroscopy (XPS) analysis indicates that the bonding states at the LaB6/H-diamond interface underwent significant evolution with temperature, which is consistent with the variation trend of Dit obtained from the electrical measurements. These results elucidate the temperature-dependent evolution of the LaB6/H-diamond interface and provide a basis for designing thermally robust Schottky contacts.