An official website of the United States government
Power devices are highly desirable to possess excellent avalanche and short-circuit (or surge-current) robustness for numerous power electronics applications like automotive powertrains, electric grids, motor drives, among many others. Current commercial GaN power device, the lateral GaN high-electron-mobility transistor (HEMT), is known to have no avalanche capability and very limited short-circuit robustness. These limitations have become a roadblock for penetration of GaN devices in many industrial power applications. Recently, through collaborations with NexGen Power Systems (NexGen), Inc., we have demonstrated breakthrough avalanche, surge-current and short-circuit robustness in NexGen’s vertical GaN p-n diodes and fin-shape junction-gate field-effect-transistors (Fin-JFETs). These large-area GaN diodes and Fin-JFETs were manufactured in NexGen’s 100 mm GaN-on-GaN fab. The demonstrated avalanche, surge-current and short-circuit capabilities are comparable or even superior to Si and SiC power devices. Additionally, vertical GaN Fin-JFETs were found to fail to open-circuit under avalanche and short-circuit conditions, which is highly desirable for the system safety. This talk reviews the key robustness results of vertical GaN power devices and unveils the enabling device physics. Fundamentally, these results signify that, in contrast to some popular belief, GaN devices with appropriate designs can achieve excellent robustness and thereby encounter no barriers for applications in electric vehicles, grids, renewable processing, and industrial motor drives.
more »
« less
The renaissance of lateral power devices for high voltage applications
Power semiconductor devices, spanning blocking voltages from a few volts to tens of thousands of volts, are critical for efficient energy conversion in numerous applications and serve as key enablers of carbon neutrality. These devices can be realized in either vertical or lateral architectures, with the former preferred for high-power discrete devices and the latter offering high switching speeds and monolithic circuit integration. While lateral structures have long been utilized in low- and medium-voltage applications, recent advancements in multidimensional device architectures and (ultra-)wide-bandgap semiconductor materials have revitalized their potential for high-voltage applications. Multidimensional architectures, such as superjunction and multichannel designs, enable uniform electric field distribution for voltage scaling and, at the same time, boost carrier concentrations to enhance current capacity. The application of these architectures in gallium nitride and gallium oxide has led to the demonstration of multi-kilovolt lateral devices with diverse designs, achieving breakdown voltages exceeding 10 000 V, average electric fields up to 4.7 MV/cm, high-temperature operation up to 250 °C, and specific on-resistances at least 2–3 times lower than similarly rated vertical devices. Such advantages can be further enhanced through the implementation of monolithic bidirectional devices, a unique capability of the lateral architecture that enables the replacement of four vertical devices. This review provides an overview of multidimensional high-voltage lateral devices, emphasizing their fundamental device physics to inspire further applications across various material systems. The theoretical performance limits of multidimensional lateral devices are also analyzed. In addition, we discuss critical knowledge gaps that must be addressed for industrial adoption, highlighting emerging research opportunities in this rapidly evolving field.
more »
« less
- Award ID(s):
- 2230412
- PAR ID:
- 10642140
- Publisher / Repository:
- APL
- Date Published:
- Journal Name:
- APL Electronic Devices
- Volume:
- 1
- Issue:
- 3
- ISSN:
- 2995-8423
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
The wide bandgap semiconductors SiC and GaN are commercialized for power electronics and for visible to UV light-emitting diodes in the case of the GaN/InGaN/AlGaN materials system. For power electronics applications, SiC MOSFETs (metal–oxide–semiconductor field effect transistors) and rectifiers and GaN/AlGaN HEMTs and vertical rectifiers provide more efficient switching at high-power levels than do Si devices and are now being used in electric vehicles and their charging infrastructure. These devices also have applications in more electric aircraft and space missions where high temperatures and extreme environments are involved. In this review, their inherent radiation hardness, defined as the tolerance to total doses, is compared to Si devices. This is higher for the wide bandgap semiconductors, due in part to their larger threshold energies for creating defects (atomic bond strength) and more importantly due to their high rates of defect recombination. However, it is now increasingly recognized that heavy-ion-induced catastrophic single-event burnout in SiC and GaN power devices commonly occurs at voltages ∼50% of the rated values. The onset of ion-induced leakage occurs above critical power dissipation within the epitaxial regions at high linear energy transfer rates and high applied biases. The amount of power dissipated along the ion track determines the extent of the leakage current degradation. The net result is the carriers produced along the ion track undergo impact ionization and thermal runaway. Light-emitting devices do not suffer from this mechanism since they are forward-biased. Strain has also recently been identified as a parameter that affects radiation susceptibility of the wide bandgap devices.more » « less
-
The wide bandgap semiconductors SiC and GaN are commercialized for power electronics and for visible to UV light-emitting diodes in the case of the GaN/InGaN/AlGaN materials system. For power electronics applications, SiC MOSFETs (metal–oxide–semiconductor field effect transistors) and rectifiers and GaN/AlGaN HEMTs and vertical rectifiers provide more efficient switching at high-power levels than do Si devices and are now being used in electric vehicles and their charging infrastructure. These devices also have applications in more electric aircraft and space missions where high temperatures and extreme environments are involved. In this review, their inherent radiation hardness, defined as the tolerance to total doses, is compared to Si devices. This is higher for the wide bandgap semiconductors, due in part to their larger threshold energies for creating defects (atomic bond strength) and more importantly due to their high rates of defect recombination. However, it is now increasingly recognized that heavy-ion-induced catastrophic single-event burnout in SiC and GaN power devices commonly occurs at voltages ∼50% of the rated values. The onset of ion-induced leakage occurs above critical power dissipation within the epitaxial regions at high linear energy transfer rates and high applied biases. The amount of power dissipated along the ion track determines the extent of the leakage current degradation. The net result is the carriers produced along the ion track undergo impact ionization and thermal runaway. Light-emitting devices do not suffer from this mechanism since they are forward-biased. Strain has also recently been identified as a parameter that affects radiation susceptibility of the wide bandgap devices.more » « less
-
While the properties of β-Ga 2 O 3 continue to be extensively studied for high-power applications, the effects of strong electric fields on the Ga 2 O 3 microstructure and, in particular, the impact of electrically active native point defects have been relatively unexplored. We used cathodoluminescence point spectra and hyperspectral imaging to explore possible nanoscale movements of electrically charged defects in Ga 2 O 3 vertical trench power diodes and observed the spatial rearrangement of optically active defects under strong reverse bias. These observations suggest an unequal migration of donor-related defects in β-Ga 2 O 3 due to the applied electric field. The atomic rearrangement and possible local doping changes under extreme electric fields in β-Ga 2 O 3 demonstrate the potential impact of nanoscale device geometry in other high-power semiconductor devices.more » « less
-
The outstanding properties of Gallium Nitride (GaN) have enabled considerable improvements in the performance of power devices compared to traditional silicon technology, resulting in more efficient and highly compact power converters. GaN power technology has rapidly developed and is expected to gain a significant market share in an increasing number of applications in the coming years. However, despite the great progress, the performance of current GaN devices is still far from what the GaN material could potentially offer, and a significant reduction of the device on-resistance for a certain blocking voltage is needed. Conventional GaN high-electron-mobility-transistors are based on a single two-dimensional electron gas (2DEG) channel, whose trade-off between electron mobility and carrier density limits the minimum achievable sheet resistance. To overcome such limitations, GaN power devices including multiple, vertically stacked 2DEG channels have recently been proposed, showing much-reduced resistances and excellent voltage blocking capabilities for a wide range of voltage classes from 1 to 10 kV. Such devices resulted in unprecedented high-power figures of merit and exceeded the SiC material limit, unveiling the full potential of lateral GaN power devices. This Letter reviews the recent progress of GaN multi-channel power devices and explores the promising perspective of the multi-channel platform for future power devices.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1063/5.0278883
