Manufacturing Radiation Tolerant Silicon Carbide Switches

The goal of this program is to streamline the manufacturing of radiation tolerant high voltage silicon carbide power MOSFETs in the US, and therefore to build a domestic supply chain. High power nuclear electric propulsion, and power processing for the implementation of the Moon vicinity/surface mission require high voltage and power semiconductor switches. To increase efficiency, and to decrease volume and weight of power systems, high voltage-based power distribution and processing networks are critically needed. MOSFETs play a crucial role for power systems typically used in the high voltage, power and frequency range. Additionally, silicon carbide (SiC) MOSFETs provide advantages over their silicon (Si) and gallium nitride (GaN) alternatives in the voltage range of interest. Silicon carbide is the most mature among the wide bandgap semiconductors in terms of fabrication and processing, offering the most direct path to radiation tolerance, as well as electrical performance. Commercial SiC power devices are tolerant of ionizing dose and displacement damage, but they suffer from single event effects. During our Phase II, we work on novel designs and process engineering methods to design more radiation tolerant silicon carbide power devices. The experiments show that we indeed achieved radiation tolerance and performance. This sequential work uses this foundation to make these radhard power devices and aims to build a long-term source for these devices employing domestic foundries. This requires creation of the supply chain for the low volume manufacture of these devices in the US for sensitive and critical applications. This also requires building the capability of mass manufacture of these devices domestically for NASA, DoD and commercial uses. To this end, we will work with two US foundries that serve critical-need as well as commercial markets.
Benefits: To address the need for high voltage radiation tolerant power devices for the future lunar microgrid, for other deep space exploration missions and bases, and for space nuclear electric propulsion, we design and fabricate radiation-tolerant high voltage silicon carbide power devices. Electric propulsion and power processing are identified as some of the critical technologies to be addressed as part of the global exploration roadmap for the implementation of the near-future Moon vicinity/surface mission. In addition, solar and nuclear electric propulsion, and extreme environment avionics with high overall shortfall ranks require high power and/or voltage circuits. The proposed work relates to five among the top fifteen shortfalls in the integrated list for civil space shortfall rankings, as written below: #2 1596: High Power Energy Generation on Moon and Mars Surfaces #6 1552: Extreme Environment Avionics #8 709: Nuclear Electric Propulsion for Human Exploration #12 1591: Power Management Systems for Long Duration Lunar and Martian Missions #13 702: Nuclear Thermal Propulsion for Human Exploration Our high voltage and current silicon carbide power transistor technology is to support NASA’s Moon to Mars goals and the Nuclear Electric Propulsion (NEP) Project’s needs for high voltage, high power transistors and diodes, as these are scaled up to megawatt power levels. Additionally, successful demonstration of this technology should enable infusion into the Radioisotope Power Systems (RPS) Program’s power processing systems and Fission Surface Power Project. We will also make high voltage but not high current versions of these devices as well. High voltage circuit applications include voltage sources for multichannel plates (MCPs) that are used in many types of analytical equipment. Of particular interest is particle detection and specifically advancing electrical circuits for electrostatic analyzers for advanced particle detection with smaller footprint instruments. CoolCAD is transitioning its wide bandgap power electronics from prototype to product lines. We envision a dual-use technology where standard devices for renewable energy, and industrial or power conversion circuit applications will lead the demand in making these silicon carbide power devices. In parallel, we will make radiation tolerant power MOSFETs that take advantage of the volume production related to these other widespread terrestrial-use products. Renewable energy has increased considerably since the turn of the century, driven largely by solar power. According to the US Department of Energy, the total capacity of solar power installed in residential and commercial applications has increased by more than 500% from that time. By leveraging the inherent flexibility of solar photovoltaics (PV), energy storage system (ESS), and the electric vehicle (EV) charging technology, the integrated systems can reduce the total capital and operational costs of these distributed energy resource (DER) assets. Uses of wide bandgap semiconductor-based power devices and next-generation silicon carbide (SiC) power devices would result in higher efficiencies in charging, solar and power conversion systems, decreasing the time for the system to pay itself off through savings. Furthermore, wide bandgap semiconductor devices can be operated at relatively high frequencies, enabling use of smaller passives. This would decrease the overall size of any DC power conversion circuit. Besides real estate savings and potentially denser installations, this would add less complexity and cost to wiring and installation. Besides standard use power devices, the radiation tolerant devices we manufacture can be used in satellites and near nuclear reactors. Of particular interest is the combined tolerance to radiation and temperature. In the case of hypersonics, not only radiation tolerance is required but also temperature hardened electronics are needed.