13 March 2018
SMI completes radiation hardness testing of gallium oxide for NASA
© Semiconductor Today Magazine / Juno PublishiPicture: Disco’s DAL7440 KABRA laser saw.
Structured Materials Industries Inc (SMI) of Piscataway, NJ, USA – which provides chemical vapor deposition (CVD) systems, components, materials, and process development services – has finished initial studies of the radiation hardness of gallium oxide (Ga2O3)-based power devices in accordance with a Small Business Innovation Research (SBIR) Phase I project funded by the US National Aeronautics and Space Administration (NASA Award No. NNX17CG70P).
The Ga2O3 films were grown on bulk doped and undoped Ga2O3 and other substrates in one of SMI’s in-house metal-organic chemical vapor deposition (MOCVD) systems. Total ionization dose (TID) and single-event effect (SEE) were used as radiation hardness testing metrics. The radiation hardness testing was conducted to determine whether the Ga2O3-based power devices were a good candidate for NASA’s Power Management and Distribution (PMAD) systems among other applications. Potential applications include power devices such as diodes and transistors that may be used in areas like power rectification and RF mixing, among many others.
“With the development of Ga2O3 power devices, we thought it important to further the determination of the space-worthiness/applicability of Ga2O3-based devices,” says Dr Serdal Okur, principal investigator for SMI SBIR Ga2O3-related projects. “Testing actual devices made this project all the more relevant. We tested different combinations of device material properties, such as orientation, doping levels, substrate dopant, and crystal growth technique, including epilayers grown by MOCVD,” he adds. “Fabricated devices included Schottky barrier diodes. The variables were strategically chosen to critically evaluate the potential of Ga2O3-based power device performance under different radiation exposures.”
The testing was carried out in stages during the Phase I project and was deemed to be a significant milestone in the overall assessment of Ga2O3 radiation hardness. All Phase I objectives were completed.
“The Phase I work of this project was implemented and successfully completed in a 6-month period, which is very impressive considering the amount of knowledge acquired from this study,” says Okur. “We are also grateful for the contributions from all the personnel at various universities, research laboratories, and government agencies that were involved in this project.”
There are three types of space radiation that are particularly concerning to space missions: particles trapped in the Earth’s magnetic field; solar particle events (particles shot into space during solar flares); and galactic cosmic rays (high-energy protons and heavy ions from outside our solar system).