300-Volt GaN FET Space Exploration: Advances in Energy Supply

Related Vendors

EPC - Efficient Power Conversion Corporation

GGB Heilbronn GmbH

In space exploration, components are particularly susceptible to radiation effects such as single-event burnout (SEB) or single-event gate rupture (SEGR). Due to the lack of atmosphere, the radiation intensity is significantly higher. Gallium nitride (GaN) technology offers substantial advantages in terms of robustness and reliability due to its design.

With the EPC7030MSH, EPC Space, a joint venture between Efficient Power Conversion (EPC) and VPT Inc., introduces a component that marks another step towards more compact, efficient, and radiation-resistant power supply systems for satellites. The transistor is the first 300-volt Rad-Hard GaN FET of its kind and is aimed at applications requiring higher bus voltages—such as electric propulsion systems, power distribution units, or onboard networks of modern communication satellites.

The FET is based on enhancement-mode GaN technology, meaning it operates as a voltage-controlled device like a MOSFET, but offers significantly higher power density. EPC Space combines this technological approach with a hermetically sealed surface-mount package, specifically designed for conduction-cooled designs in satellites. This enables the realization of power converters with high packaging density and reduced weight—two critical factors in space applications.

Technical classification and application framework

With a drain-source breakdown voltage (V_DSS) of 300 V, the EPC7030MSH expands the previously available voltage range of radiation-hardened GaN FETs. According to the manufacturer, the component is designed for Linear Energy Transfer values (LET) of up to 84.6 MeV (300 V: LET = 63 MeV, 250 V: LET = 84.6 MeV), thereby demonstrating exceptional resistance to single-event effects (SEE).

The combination of low on-resistance and low gate charge enables high switching frequencies with minimal losses. For system designers, this means smaller magnetics, more compact filters, and overall higher power density. This is a significant advantage, especially in satellite onboard power supply systems, where every gram of weight matters.

The package design further enhances robustness. With extended creepage distances and hermetic sealing, it meets the requirements for space and high-voltage environments. The component is intended for use in DC-DC front ends, power distribution systems, and high-performance motor controls.

GaN under radiation—Material physics as an advantage

The radiation tolerance of GaN components is not solely the result of special protective measures but is largely a consequence of the material itself. Gallium nitride belongs to the so-called wide bandgap semiconductors, whose band gap, at approximately 3.4 eV, is about three times larger than that of silicon. This wide band gap reduces the likelihood of ionizing radiation generating free charge carriers in the material, which could alter parameters such as threshold voltage or leakage currents.

In addition, GaN's high "displacement threshold energy" means significantly more energy is required to displace an atom in the crystal lattice compared to silicon. As a result, fewer lattice defects occur under neutron or proton bombardment.

Another point concerns the device architecture. In GaN FETs, a thin AlGaN barrier separates the gate from the conducting channel. This structure does not accumulate ionized charge when exposed to gamma radiation. This is a significant difference compared to silicon MOSFETs, where oxide charges build up in the gate dielectric and can alter the switching characteristics over time.

Comparison to silicon MOSFETs

Rad-hard MOSFETs based on silicon are considered established and well-characterized, but they are increasingly reaching their physical limits in modern high-performance satellite systems. Under Total Ionizing Dose (TID) conditions, Si-MOSFETs often experience gate threshold drift, increased leakage, and reduced lifespan.

GaN FETs demonstrate significantly more stable characteristics in these tests. Studies by the NASA NEPP initiative and various space laboratories confirm that the variation in key parameters remains minimal even after irradiation with several Mrad. This enables designers to apply more conservative derating factors, leading to more efficient utilization of the component.

Moreover, the higher efficiency of GaN is not only energetically advantageous but also thermally significant: less power loss means reduced thermal stress and, consequently, lower susceptibility to radiation-induced aging effects.

Challenges and limitations

Despite the inherent advantages, radiation hardening remains a systemic process. Even GaN components can be damaged by single-event burnout (SEB) or gate rupture (SEGR) if voltage spikes exceed critical levels. Packaging, layout, and design are therefore just as crucial as material selection.

GaN components like the EPC7030MSH are essential for radiation-hardened power electronics. With the 300-volt V_DSS, satellites with significantly higher performance are now possible. The higher bus voltages result in weight reduction, which is indispensable in space exploration.

GaN technology proves not only to be more efficient but also more resistant to radiation effects. Overall, the new EPC FET represents the transition to a generation of space power components that achieve robustness not solely through protective measures but through their material itself.
(mr)