Wide-bandgap semiconductors have made and are continuing to make a major impact on the power electronics world. The most common commercially available wide-bandgap semiconductors for power electronics applications are SiC and GaN devices. This paper focuses on the newest devices emerging that are made with these wide-bandgap materials. The static and dynamic characterization of six different SiC MOSFETs from different manufacturers are presented. The static characterization consists of the output characteristics, transfer characteristics and device capacitances. High temperature (up to 150 °C) static characterization provides an insight into the dependence of threshold voltage and on-state resistance on temperature. The dynamic characterizations of the devices are conducted by performing the double-pulse test. The switching characteristics are also tested at high temperature, with the presented results putting an emphasis on one of the devices. A comparison of the key characterization results summarizes the performance of the different devices. The characterization of one of the SiC MOSFETs is then continued with a short-circuit failure mode operation test. The device is subjected to non-destructive and destructive pulses to see how the device behaves. The non-destructive tests include a look at the performance under different external gate resistances and drain-source voltages. It is found that as the external gate resistance is increased, the waveforms get noisier. Also, as the drain-source voltage is increased, the maximum short-circuit current level rises. The destructive tests find the amount of time that the device is able to withstand short-circuit operation. At room temperature the device is able to withstand 4.5 μs whereas at 100 °C, the device is able to withstand 4.2 μs. It is found that despite the different conditions that the device is tested at for destructive tests, the energy that they can withstand is similar. This paper also presents the static and dynamic characterization of a 600 V, 2A, normallyoff, vertical gallium-nitride (GaN) transistor. A description of the fabrication process and the setup used to test the device are presented. The fabricated vertical GaN transistor has a threshold voltage of 3.3 V, a breakdown voltage of 600 V, an on-resistance of 880 mΩ, switching speeds up to 97 V/ns, and turn-on and turn-off switching losses of 8.12 µJ and 3.04 µJ, respectively, demonstrating the great potential of this device / MS / A key part in a power electronics circuit is the switch component. Currently, the devices usually used as the switch are made from silicon. As the performance limits of silicon are reached though, wide-bandgap semiconductors are proving to be a promising alternative to silicon semiconductors. These wide-bandgap switches will allow for higher powers, higher efficiency and higher temperature operation. The technology is still novel though and so new devices are still being developed. This paper focuses on showing the performance of the newest devices emerging that are made with these wide-bandgap materials. To demonstrate the performance potential of a switching device, the non-switching and switching behavior need to be tested. These tests are described and the results are shown for both Silicon Carbide (SiC) and Gallium Nitride (GaN) semiconductors which are the most common wide bandgap semiconductors. The failure mode operation of one of the SiC devices is also tested. A common failure in power electronics is a short circuit failure where the switch is turned on for a long amount of time and kept on for too long, eventually leading to the device breaking destructively. To understand the limits and capabilities of these devices in a short circuit failure, non-destructive and destructive tests are explained and demonstrated.

This paper describes the design, fabrication, and testing of a 1.2 kV, 6.5 mΩ, half-bridge, SiC MOSFET power module to evaluate the impact of parametric device tolerances on electrical and thermal performance. Paralleling power devices increases current handling capability for the same bus voltage. However, inherent parametric differences among dies leads to unbalanced current sharing causing overstress and overheating. In this design, a symmetrical DBC layout is utilized to balance parasitic inductances in the current pathways of paralleled dies to isolate the impact of parametric tolerances. In addition, the paper investigates the benefits of flexible PCB in place of wire bonds for the gate loop interconnection to reduce and minimize the gate loop inductance. The balanced modules have dies with similar threshold voltages while the unbalanced modules have dies with unbalanced threshold voltages to force unbalanced current sharing. The modules were placed into a clamped inductive DPT and a continuous, boost converter. Rogowski coils looped under the wire bonds of the bottom switch dies to observe current behavior. Four modules performed continuously for least 10 minutes at 200 V, 37.6 A input, at 30 kHz with 50% duty cycle. The modules could not perform for multiple minutes at 250 V with 47.7 A (23 A/die). The energy loss differential for a ~17% difference in threshold voltage ranged from 4.52% (~10 µJ) to -30.9% (~30 µJ). The energy loss differential for a ~0.5% difference in V_th ranged from -2.26% (~8 µJ) to 5.66% (~10 µJ). The loss differential was dependent on whether current unbalance due to on-state resistance compensated current unbalance due to threshold voltage. While device parametric tolerances are inherent, if the higher threshold voltage devices can be paired with devices that have higher on-state resistance, the overall loss differential may perform similarly to well-matched dies. Lastly, the most consistently performing unbalanced module with 17.7% difference in V_th had 119.9 µJ more energy loss and was 22.2°C hotter during continuous testing than the most consistently performing balanced module with 0.6% difference inV_th. / Master of Science / This paper describes the design, construction, and testing of advanced power devices for use in electric vehicles. Power devices are necessary to supply electricity to different parts of the vehicle; for example, energy is stored in a battery as direct current (DC) power, but the motor requires alternating current (AC) power. Therefore, power electronics can alter the energy to be delivered as DC or AC. In order to carry more power, multiple devices can be used together just as 10 people can carry more weight than 1 person. However, because the devices are not perfect, there can be slight differences in the performance of one device to another. One device may have to carry more current than another device which could cause failure earlier than intended. In this research project, multiple power devices were placed into a package, or "module." In a control module, the devices were selected with similar properties to one another. In an experimental module, the devices were selected with properties very different from one another. It was determined that the when the devices were 17.7% difference, there was 119.9 µJ more energy loss and it was 22.2°C hotter than when the difference was only 0.6%. However, the severity of the difference was dependent on how multiple device characteristics interacted with one another. It may be possible to compensate some of the impact of device differences in one characteristic with opposing differences in another device characteristic.