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

Abstract

In this letter, we identified a dominant buffer trapping causing a bias-dependent dynamic $R_{\mathrm{\scriptscriptstyle ON}}$ for 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 $E_{C}-0.60$ 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 $R_{\mathrm{\scriptscriptstyle ON}}$ of 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.