Cubic BN Diodes and Transistors

In support of missions to the Moon, Mars, and the Sun, NASA needs high-voltage, high-current power electronic components that tolerate heavy-ion-radiation-induced damage without catastrophic failure. Diodes with 1200V 40A capability and transistors that operate at 600V 40A (after any needed de-rating for operation in high radiation environments) are desired for use in space-based power systems. Even after ~25 years of development, space-qualified GaN components are limited to 300V operation in space. In 2014, Hirama and colleagues at NTT demonstrated the MBE growth of cubic BN [1-2] on (100) diamond substrates. In 2022, Storm [3] at NRL reproduced the Japanese MBE growth result. In 2022, OSEMI custom-built a c-BN MBE system in the configuration described by Hirama and utilized it to demonstrate the initial growth of c-BN epitaxial layers in 2023. In our recently completed NASA Phase I effort, OSEMI brought an MBE machine up and used it to grow BN-on-Silicon wafers. Our Phase II effort proposes to continue and extend our preliminary work on c-BN epitaxy to lower defect density, establish n-type and p-type doping in c-BN, and make diodes and MESFET and Gate Injection Transistors (GIT) in c-BN. Initially, the growth and processing of n and p-type diode samples and diodes will be investigated on 2-inch diameter substrates. We will also attempt the growth and fabrication of a lateral c-BN MESFET followed by a c-BN Gate Injection Transistor with further refinements of all three devices, potentially including radiation tolerance life testing in a Phase II sequential program. The goal of this first Phase II effort will be to establish the growth and fabrication technology for the proposed c-BN MESFET and GIT transistors, complete device characterization and one round of standard life testing, and achieve a new generation of c-BN Power Electronic Components and RF devices to provide a foundation for a next generation of chemically inert radiation tolerant power subsystems.