Impact of triangle-like defect in 4H-SiC epitaxial layers on the electrical characteristics of SiC bipolar device

Silicon carbide (SiC) power devices with intrinsic material advantages over silicon have attracted tremendous attention in the past two decades, yet elucidating the failure mechanism of devices induced by defects remains intractable challenges. This work systematically investigates the relationship between triangle-like defects and electrical performance of 1200V 4H-SiC Merged PiN Schottky Bipolar (MPS) on four complete wafers. Triangle-like defects are categorized into two types named Pit Triangle and Shallow Triangle respectively according to their surface topography. Through comprehensive electrical characterization and microstructural analysis, we establish that these geometrically similar defects exhibit fundamentally different impacts on device functionality. The results of I-V measurement display that the Pit Triangle defects can markedly increase leakage current, whereas Shallow Triangle defects cause negligible performance degradation. In addition, it is noted that diverse failure cases are caused by different locations of the Pit Triangle defect on the device. Through the integration of microstructural characterization and energy band theory, the underlying mechanism by which Pit Triangle defects act as killer defects for SiC power device has been mechanistically elucidated. This work further explores the triangle-like defects and analyzes the correlation between device failure with triangle-like defects, which are essential towards enhancing manufacturing yield and operational reliability of SiC power devices.