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Gallium Nitride (GaN) power devices can offer better switching performance and higher efficiency than Silicon Carbide (SiC) and Silicon (Si) devices in power electronics applications. GaN has extensively been incorporated in electric vehicle charging stations and power supplies, subjected to harsh environmental conditions. Many reliability studies evaluate GaN power devices through thermal stresses during current conduction or pulsing, with a few focusing on high blocking voltage and high humidity. This paper compares GaN-on-Si High-Electron-Mobility Transistors (HEMT) device characteristics under a High Humidity, High Temperature, Reverse Bias (H3TRB) Test. Twenty-one devices from three manufacturers were subjected to 85 °C and 85% relative humidity while blocking 80% of their voltage rating. Devices from two manufacturers utilize a cascade configuration with a silicon metal-oxide-semiconductor field-effect transistor (MOSFET), while the devices from the third manufacturer are lateral p-GaN HEMTs. Through characterization, three sample devices have exhibited degraded blocking voltage capability. The results of the H3TRB test and potential causes of the failure mode are discussed. [ABSTRACT FROM AUTHOR]

As power electronic applications continue to switch higher levels of voltage and current in smaller-sized component packages, the resulting increase in power density requires efficient thermal management. This paper compares the thermal performance for operating a metal-oxide-semiconductor field-effect transistor on a water-cooled pole-arrayed heat sink versus a novel water-cooled microchannel heat sink. Details are presented on an innovative technique using Fourier analysis techniques for determining the thermal capacitance modeling parameter for the heat sinks from experimental data. [DOI: 10.1115/1.2814056]

The U. S. Army Research Laboratory (ARL) is evaluating silicon carbide thyristors to determine the extent of silicon carbide capabilities as a possible replacement for silicon in future pulsed switching applications. Individual SiC die measuring 4 mm x 4 mm were pulsed at high temperatures and varying pulse widths. At 150[degrees]C, these thyristors were switched in an RLC circuit up to 3.2 kA and repetitively pulsed at 2.6 kA and 5 Hz for greater than 14,000 pulses. A pulse forming network (PFN) was designed to increase the pulse width and the action seen by the SiC devices. At ambient temperature and a peak current of 2 kA, SiC thyristors were switched in the PFN at a 50% pulse width of 40 [micro]s and an action of 150 [A.sup.2]s. These devices were also pulsed at narrower pulse widths in pairs to look at their behavior in parallel. One pair reached a peak total current of 6.7 kA with current sharing as good as 51% / 49%. This paper includes further data on the three aforementioned test procedures, as well as analysis of the devices' failure points. Index Terms--Thyristors, resistance heating, pulse shaping circuits, pulse power system switches, semiconductor switches, semiconductor materials, semiconductor device breakdown, power semiconductor switches.

Super gate turn-off thyristors (SGTOs) implemented in both silicon (Si) and silicon carbide (SIC) semiconductors were investigated for high-voltage, high-current pulsed power applications. Modular 80 and 400 kA switches implemented in silicon (2.0-[cm.sup.2] dies) and individual SiC switch die (0.16 [cm.sup.2]) were evaluated. The Si 80- and 400-kA switches were demonstrated (at ambient temperature) to provide rates of current rise (10%-90% peak current) and peak currents (145-[micro]s width) of 24 kA/[micro]s and 92 kA; and 40 kA/[micro]s and 400 kA, respectively. The Si 80-kA switch was repetitively pulsed 1000 times with no significant performance degradation. The SiC switch die were demonstrated to provide specific rate of current rise and current density of 49 kA/[micro]s/[cm.sup.2] and 56.1 kA/[cm.sup.2], which are at least 2.5 times greater than are possible in silicon pulse switches. The SiC switches were repetitively pulsed at 5 Hz up to 99 000 times without failure and were demonstrated to operate at case temperatures up to 150 [degrees]C. Index Terms--Power semiconductor switches, pulse power system switches, pulse shaping circuits, silicon.

SiC GTO thyristors may soon be the best available choice for very high-power switching. At this time, we have developed new operational techniques, growth requirements and pn-pn-pn type structures to address the issues of high on-state voltage, poor turn-off gain, and inability to reach predicted breakover voltages. We present these findings using experimental measurements and numerical simulations. Index Terms--Power semiconductor devices, power semiconductor switches, semiconductor device modeling, semiconductor device reliability, thyristors.