Imaging current transport across Schottky interface with diamond Nitrogen-Vacancy centers magnetometry

Schottky barrier diodes (SBDs) are a key component of high-efficiency power electronics, valued for their low voltage drop and fast switching speed. Of particular interest are SBDs based on wide-bandgap semiconductor (WBS), such as on SiC or GaN, due to their superior breakdown voltage, lower losses, and excellent thermal stability compared to Si devices. However, metal-semiconductor interface instabilities leading to inhomogeneous charge transport remain a major challenge in developing reliable WBS SBDs, particularly for the more scalable vertical SBD architecture.

To characterize such instabilities, we employ diamond nitrogen-vacancy (NV) center magnetometry to image current transport across the Schottky interface. NVs-based magnetometry offers micron-scale spatial resolution, millimeter-scale field of view, high sensitivity, and non-invasive magnetic field imaging. Using an NV ensemble, we map the magnetic fields produced by current flow in an SBD and reconstruct the corresponding current density to estimate the likelihood to identify transport inhomogeneities and device failures. Experimental data are compared with finite-element simulations.

We anticipate that visualizing charge transport across SBDs affected by inhomogeneity and defects might become an essential tool for the development of next-generation vertical WBS Schottky diodes.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525