Bipolar Conduction Impact on Electrical Characteristics and Reliability of 1.2- and 3.5-kV 4H-SiC JBS Diodes

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> 4H-SiC Junction Barrier Schottky (JBS) diodes (1.2 and 3.5 kV) have been processed using the same technology with two different layouts. From 4 A and for the whole temperature range, the 3.5-kV diodes exhibit a bipolar conduction independent of the layout. However, the behavior of the 1.2-kV diodes depends on the design. At 500 V–300 <formula formulatype="inline"> <tex>$^{\circ}\hbox{C}$</tex></formula>, the leakage current is only 100 nA and 10 <formula formulatype="inline"><tex>$\mu\hbox{A}$</tex></formula> for the 3.5- and 1.2-kV diodes, respectively. The switch-off performances show a reverse peak current of only 50% of the nominal current at 300 <formula formulatype="inline"><tex>$^{\circ}\hbox{C}$</tex></formula> for all JBS diodes. The JBS diodes have a surge current capability of around 80 A, two times higher than the Schottky diodes. DC electrical stresses are performed during 50 h, and all the 1.2-kV diodes exhibit no bipolar degradation. Nevertheless, some slight bipolar degradation is observed in 3.5-kV JBS diodes. Electroluminescence measurements exhibit the expansion of stacking faults in 3.5-kV diodes unlike in 1.2-kV diodes. </para>