Bernhard Ruch Dipl.-Ing. Dr.techn. Publications

Biography Bernhard Ruch was born in Klagenfurt, Austria in 1990. He holds an B.Sc. and M.Sc in technical physics from TU Wien which he acquired in 2014 and 2016, respectively. In 2021 he obtained his doctoral degree from TU Wien. During his doctoral research, which has been performed at KAI in Villach, he focused on the characterization and modeling of hot-carrier degradation in planar and trench power MOSFETs. Bernhard joined TU Wien in Mai 2024, where he is employed as postdoctoral researcher focusing on GaN power devices.

This study investigates the role of a two-dimensional hole gas (2DHG) in GaN-based gate injection transistors (GITs) with and without an AlGaN back-barrier (BB). The presence of a 2DHG in BB-equipped devices is confirmed via electroluminescence (EL) measurements, which show hole spreading beyond the gate area - unlike in conventional (CONV) devices, where EL is confined to the gate. This spread facilitates faster dynamic RDSon recovery after off-state stress.

The research compares the recovery behavior of both device types through electrical measurements and TCAD simulations. In BB devices, holes injected from the gate quickly distribute laterally along the BB interface, forming a 2DHG that accelerates recovery by neutralizing trapped charges in the buffer. Conversely, in CONV devices, recovery is slower and occurs in two phases due to localized hole accumulation beneath the gate.

Simulations further validate that recovery dynamics in BB devices are significantly improved despite requiring lower gate current. This finding challenges the assumption that high gate current is essential for effective recovery, suggesting instead that hole distribution efficiency is the key factor.

The study provides direct evidence of 2DHG formation and underscores the performance benefits of integrating a BB in GaN GITs, which enhances robustness and reduces RDSon degradation in power switching applications.