2D Electric field imagery in 4H-SiC power diodes using OBIC technique

Abstract

Wide band gap semiconductors are more and more used, especially to design high voltage devices. However, some devices show lower breakdown voltages than those predicted in theory. These early breakdown are in general due to imperfections in the peripheral protections of the active junction. The aim of these protections is to reduce electric field peaks at the periphery of the junction. Thus, it is important to study the electric field distribution on the device periphery to detect any protection weakness. This paper presents a 2D electric field imagery using OBIC (optical beam induced current) technique. 2D cartographies are realized on JTE (junction termination extension) protected diodes in order to display electric field on diode peripheries. Other measurements are also performed on circular avalanche diodes protected with a MESA etching and provided with optical window. In both cases, OBIC techniques is demonstrated to be an efficient method to obtain electric field distribution within the device and to locate defects.