Fully-vertical GaN-on-SiC Schottky barrier diode with ultrathin AlGaN buffer layer

Abstract

In this letter, vertically conductive GaN epilayer on SiC substrate was achieved without the typically used conductive buffer layer. Here, in order to reduce the impacts of band offset of different layers on vertical conductivity and improve the vertical carrier transportation, an ultrathin AlGaN buffer layer was employed to replace the thick conductive buffer layer. Fully-vertical Schottky barrier diode (SBD) based on this vertically conductive epi-stack demonstrated a much lower specific on-resistance of 0.84 mΩ∙cm2 with superior thermal stability. Moreover, the SBD also exhibited an on/off ratio of ~5×109 and a nearly unity ideality factor of 1.08. This approach lays the foundation for the heterogeneous integration of GaN/SiC based devices.