Analytical Model and Design Strategy for GaN Vertical Floating Island Schottky Diodes

Abstract

We report GaN-based vertical Schottky barrier diodes (SBDs) with embedded floating islands (FIs). The incorporation of FI structure can break the theoretical limit of unipolar vertical GaN devices by homogenizing the electric field distribution within the drift layer. To facilitate comprehensive understanding and structural design of FI SBDs, analytical models for both conducting state and blocking state of GaN FI SBDs are established and verified by TCAD simulation. Parametric optimization for the reverse characteristics of GaN FI SBDs is also carried out systematically. We found that the doping concentration, height of p-GaN FIs, and spacing between adjacent p-GaN FIs are closely associated with the electric field distribution and the reverse breakdown characteristics of vertical FI SBDs. An optimum Baliga’s figure of merit (FOM) of 4.98 GW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> can be achieved, which features a 79.14% enhancement compared with the conventional SBD. The results can provide systematic design guidelines for GaN vertical power electronic systems toward high-voltage, high-speed, and high-power applications.