High-bandwidth current-probing techniques for the dynamic characterization of wide-bandgap semiconductor devices

The continuous demand for higher efficiency and power density drives the development of modern power electronics, particularly in mobile applications. Wide-bandgap (WBG) semiconductors are key enablers, offering high switching speeds and low losses. Accurate dynamic characterization via the double-pulse test is essential to optimize these devices. It has been verified that the parasitic inductance and the limited bandwidth of the current probe are among the most critical variables for achieving reliable measurement results. Common solutions, such as coaxial shunts with an inductance of approx. 2 nH, are unsuitable for measuring very fast switching transients, as they introduce significant disturbances. This dissertation introduces a novel shunt resistor based on radially arranged thin-film resistors. The design minimizes the inductance to below 100 pH and offers a usable bandwidth beyond 2 GHz. Additionally, an inductive sensor is designed as a reference. It is based on a planar pick-up coil embedded in a multilayer circuit board and achieves a similar bandwidth. Both methods were validated with a low-inductive Gallium Nitride switching cell. The results demonstrate that the radial shunt resistor outperforms existing solutions for the dynamic characterization of WBG semiconductors. Its high accuracy, combined with an innovative design and an easy-to-reproduce assembly technique, makes it a valuable tool for advancing power electronics. This work establishes a new standard for high-frequency current measurements, pushing the boundaries of precision in WBG semiconductor characterization.