Ultrawide Bandgap Lateral AlN Schottky Barrier Diodes With Graded AlGaN Contact Layer on Single‐Crystal AlN Substrate

Lateral AlN Schottky barrier diodes with a top graded AlGaN contact layer were demonstrated on single‐crystal AlN substrates, where the Ohmic contact showed nearly linear behaviors with a low contact resistivity of 1.54 × 10 −3 Ω cm 2 . The device exhibited good rectifying characteristics with a high on/off ratio of 10 7 –10 9 , an ideality factor of 2.94–1.07, and a Schottky barrier height of 1.24–2.06 eV from 298 to 573 K. The device's inhomogeneous Schottky barrier distribution was also comprehensively studied. The device breakdown voltage exceeded 640 V with a high average breakdown electric field of 129 V μm − 1 .