研究目的
To examine the mechanisms of device failure due to excess surge current by analyzing variation of failure current with device current and voltage ratings, as well as duration of current surge, and to quantify the impact of the resistance of the anode ohmic contact to the p-shielding region on surge current capability.
研究成果
MPS designs significantly increase the failure current and provide a design advantage at current pulse width of 10 μs, but not at 8.3 ms. Failure signature in de-capped devices is melt-over of anode metal over termination region, reducing blocking capability. Energy dissipation at failure increases with pulse width in the 10 μs regime whereas failure current density remains stable, but this increase of energy dissipation at failure saturates in the 8.3 ms regime, indicating a transition from current density threshold to energy dissipation threshold for failure at higher pulse-widths.
研究不足
The study focuses on SiC JBS and MPS diodes, and the findings may not be directly applicable to other types of diodes or materials. The experimental setup and conditions are specific to the devices and parameters tested.
1：Experimental Design and Method Selection:
GPTG’s SiC diodes with and without MPS ohmic contacts were subjected to forward surge currents and tested for failure. 10 μs long current pulses were generated by a custom laser pulse generator, and passed through the device in forward bias. The current through and voltage across the device were measured with a Tektronix oscilloscope.
2：Sample Selection and Data Sources:
A sample of 10 parts of each device type was selected for each test.
3：List of Experimental Equipment and Materials:
Custom laser pulse generator, Tektronix oscilloscope, TO-220 packages, pneumatic actuator switch, Tektronix 371A curve tracer, power-frequency transformer.
4：Experimental Procedures and Operational Workflow:
Devices were subjected to one surge current pulse, device parameters were re-confirmed for goodness, and then amplitude of the surge pulse increased until device parameters degraded.
5：Data Analysis Methods:
The amplitude of current and voltage of the final surge pulse applied before failure was recorded as the failure current and voltage of the part. Average failure current and voltage across the 10 samples was then calculated.
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