Vertical GaN Switches for EV

Advancement of the performance and reliability of power electronics utilizing wide bandgap materials has been identified as a key technical target by the US DRIVE partnership to meet 2025 roadmap targets established by the Department of Energy’s Vehicle Technologies Office (VTO). While SiC-based technology has a significant head-start over GaN in terms of its technical maturity and is being ramped up for adoption, the superior materials properties of GaN should allow for higher performing and less costly power electronics for electric vehicle applications. Despite the superior materials properties, GaN power devices do not currently perform at their theoretical limit when considering devices operating at voltages >600V. In order to obtain GaN power devices that can meet GaN’s theoretical limit in higher voltage applications applicable to EVs, high crystallinity GaN drift layers must be grown on native (bulk) GaN substrates and a vertical device architecture must be adopted. In this work, Kyma Technologies will utilize an alternative growth technique, hydride vapor phase epitaxy, to satisfy the simultaneous needs of both very thick and lightly n- doped GaN required to realize high quality epilayers for high voltage (1.2kV and higher) vertical switching transistors. Kyma is partnered with Odyssey Semiconductor, who has demonstrated a novel approach to realizing selective p-GaN doping which has opened the door to realizing manufacturable and reliable high voltage GaN transistors. Odyssey will apply this technique to Kyma-grown films in Phase I and demonstrate vertical GaN transistors operating at 1.2kV with on-resistances better than equivalent SiC-based devices. In addition to EV applications, if high voltage vertical GaN switches were to become a reality, it could open the door to increased energy efficiency in other sectors which are reliant on Si-based power electronics such as industrial motor drives, PV inverters, and potentially inverters for wind turbines.