Leakage Current Mechanisms in Reverse Biased High-Voltage 4H-SiC Power Diodes

Today’s commercial 4H-SiC power diodes contain an abundance of threading screw dislocations (TSDs) and threading edge dislocations (TEDs). It is not clear exactly how these crystal defects manifest on the performance and reliability of high-voltage power devices. In this paper, extensive current-voltage (I-V) and capacitance-voltage (C-V) measurements of 600V, 1200V and 1700V commercial SiC power diodes at temperatures ranging from 22ºC to 250ºC will be reported. Detailed analysis of leakage current mechanisms is performed and it is shown that space charge limited current (SCLC) is a significant contributor to diode leakage current especially at increased electric fields. The static I-V data will be correlated with defect delineation using in-situ hard X-rays and it is shown that TSDs get excited first under high field stress conditions.