Dynamic Modeling and Power Loss Analysis of High-Frequency Power Switches Based on GaN CAVET

The focus of this paper is to understand the impact of the material properties of GaN, exploited using a vertical device, in power switching by estimating switching loss. The study was performed with a cascoded current aperture vertical electron transistor (CAVET). The normally OFF device was simulated and analyzed using a Silvaco ATLAS 2-D drift diffusion model integrated to SPICE-based circuit simulator. Besides evaluating the performance space and, hence, potential application space for GaN CAVETs, this paper presents significant accomplishment in establishing a device to circuit model, thereby, offering a reliable method of evaluating GaN-based power transistors. The accuracy of the model was established through the excellent agreement of simulated data with the data sheet specs of a commercial cascoded GaN high electron mobility transistor. The model was successfully applied to compare SiC MOSFETs with GaN CAVETs. A cascoded GaN CAVET has 2x faster switching time, 3x lower switching loss compared with standard commercial SiC MOSFET, owing to the higher electron mobility in GaN. Operating at frequencies of megahertz with low power loss, a GaN CAVET will, therefore, lead to smaller converter size and higher system efficiency.