On the Identification of Buffer Trapping for Bias-Dependent Dynamic RONof AlGaN/GaN Schottky Barrier Diode With AlGaN:C Back Barrier

In this letter, we identified a dominant buffer trapping causing a bias-dependent dynamic RONfor AlGaN/GaN Schottky barrier diodes (SBDs) fabricated on a C-doped AlGaN buffer as back-barrier. Current transient measurements at various temperatures were performed simultaneously on an AlGaN/GaN SBD and a transmission line model (TLM) structure based on the AlGaN/GaN heterojunction. During the stress of the TLM structure, the two Ohmic contacts are biased at the same voltage forming an equipotential surface while creating a uniform vertical electrical field to induce buffer trapping. We extracted the same dominant trap level of EC- 0.60 eV from the current transient spectroscopy on both the AlGaN/GaN SBD and the TLM structure after stressing at -100 V, indicating that the increase in the dynamic RONof the diode is due to the electron trapping in the buffer layers. More electron filling of this buffer trap occurs at higher stressing voltages (from -50 to -200 V), which reflects in an enhanced current-transient amplitude at the same time-constant under higher stressing voltages.