High-current, high-voltage AlN Schottky barrier diodes
Cristyan Quiñones-García, Dolar Khachariya, Pramod Reddy, Seiji Mita, Jack Almeter, Pegah Bagheri, Shashwat Rathkanthiwar, Ronny Kirste, Spyridon Pavlidis, E. Kohn, Ramón Collazo, Zlatko Sitar
Abstract
AlN Schottky barrier diodes with low ideality factor (<1.2), low differential ON-resistance (<0.6 mΩ cm 2 ), high current density (>5 kA cm −2 ), and high breakdown voltage (680 V) are reported. The device structure consisted of a two-layer, quasi-vertical design with a lightly doped AlN drift layer and a highly doped Al 0.75 Ga 0.25 N ohmic contact layer grown on AlN substrates. A combination of simulation, current–voltage measurements, and impedance spectroscopy analysis revealed that the AlN/AlGaN interface introduces a parasitic electron barrier due to the conduction band offset between the two materials. This barrier was found to limit the forward current in fabricated diodes. Further, we show that introducing a compositionally-graded layer between the AlN and the AlGaN reduces the interfacial barrier and increases the forward current density of fabricated diodes by a factor of 10 4 .