The impact of triangular defects on electrical characteristics and switching performance of 3.3kV 4H-SiC PiN diode

摘要

In this work the impact of a surface morphological defect, i.e. the triangular defect on fabricated 4H-SiC PiN diodes is explored. Diodes are intentionally fabricated on triangular defects on wafers with 35 (PiN1), and 30 (PiN2) μm 4H-SiC epitaxial layers in order to understand their impact on the resulting electrical characteristics and switching performance. We show for the first time the impact of triangular defects on switching characteristics of 3.3kV SiC PiN diodes fabricated on and off-defects and prove that the existence of triangular defects limit the active area of the devices and creates a short through the drift region, which increases the leakage current by almost 3.5×106 times than the devices off-defect. TEM images obtained from the defects verified these electrical results. Also, the reverse characteristics show that both substrates suffer from soft breakdown. The switching results show that the presence of triangular defects does not negatively affect the carrier lifetime of devices on-defect. In contrary, there is some evidence (especially in lower current values) that the amount of stored charge is increased. However, this depends on the ratio of defect to the active area of the devices.