Effect of Stacking Faults Originating from Half Loop Arrays on Electrical Behavior of 10 kV 4H-SiC PiN Diodes

Abstract

The effects of Shockley stacking faults (SSFs) that originate from half loop arrays (HLAs) on the forward voltage and reverse leakage were measured in 10 kV 4H-SiC PiN diodes. The presence of HLAs and basal plane dislocations in each diode in a wafer was determined by ultraviolet photoluminescence imaging of the wafer before device fabrication. The SSFs were expanded by electrical stressing under forward bias of 30 A/cm2, and contracted by annealing at 550 °C. The electrical stress increased both the forward voltage and reverse leakage. Annealing returned the forward voltage and reverse leakage to nearly their original behavior. The details of SSF expansion and contraction from a HLA and the effects on the electrical behavior of the PiN diodes are discussed.

SiC Power Devices in a Soft Switching Converter, Including Aspects on Packaging

“…Ten randomly selected diodes with the same design were operated for 200 h conducting a current of 0.5 A. All diodes showed stable operation and no indication of increased voltage drop, characteristic of bipolar degradation [7], was observed.…”

Unexpected Sources of Basal Plane Dislocations in 4H-SiC Epitaxy

“…The expanding stacking faults degrade the drift conductivity by a combination of suppressing carrier lifetime and introducing conduction barriers (3)(4)(5). The stacking faults also increase the reverse-bias leakage and decrease the breakdown voltage (6,7). The same degradation is observed in unipolar devices, which during operation can have conductivity modulation such as MOSFETs in which the body diode is forward biased (6).…”

“…The extent of the BPD glide and the size of the HLA can be several centimeters in thick epitaxy, typically 100 µm or more. Any device through which the HLA passes is subject to threshold voltage drift and reversed-bias leakage (7).…”

Design and Characterization of Newly Developed 10 kV 2 A SiC p-i-n Diode for Soft-Switching Industrial Power Supply

“…15 shows the measured results of the forward voltage drop stability and 10 randomly selected diodes with the same design were operated for 200 h conducting a current of 0.5 A. All diodes showed stable operation and no indication of increased forward voltage drop, characteristic of bipolar degradation [5], was observed. This result indicates that the applied buffer layer technology is efficiently converting BPDs into TEDs and prevents the p-i-n diodes from degrading during forward operation.…”

“…The breakthrough developments took place during recent years with respect to carrier lifetime enhancement [3], [4], however, the other challenges remain [5]. For switching applications, also the dynamic ON-state voltage needs to be considered.…”