Material and electrical characterization of ultrawide bandgap BN/AlN metal-insulator-semiconductor (MIS) Schottky diodes

Devices based on ultrawide bandgap heterostructures are attracting increased attention for applications that require high fields or high-temperature environments. In this article, we demonstrate an ultrawide bandgap BN/AlN metal-insulator-semiconductor Schottky diode on single-crystal AlN substrates, where the AlN epilayers were grown via metalorganic chemical vapor deposition, and the BN layer was deposited using microwave plasma chemical vapor deposition. The BN/AlN heterostructure was characterized by x-ray photoelectron spectroscopy, transmission electron microscopy, and electron-energy-loss spectroscopy. Capacitance-frequency measurements indicated a low interface state density of 0.67–3.55 × 1011 eV−1 cm−2 at the BN/AlN interface. At forward bias, the device showed good rectifying behavior. At reverse bias, 2D variable range hopping and trap-assisted tunneling were found to be the dominant mechanisms. This work provides valuable guidance for developing ultrawide bandgap nitride heterostructures.