1200V GaN Switches on Sapphire: A low-cost, high-performance platform for EV and industrial applications

We present 1200V GaN switches on sapphire substrates with fast-switching and low loss, extending the high performance of GaN switches to higher voltage levels. Sapphire substrates enable 1200V blocking voltage with low leakage while keeping epitaxy costs low compared to GaN-on-Si for similar voltages. For testing, 70 mΩ, 2-chip normally-off GaN FETs were packaged in TO-247 packages. >99% efficiency was obtained for 900:450V hard-switched buck converter operating at 50kHz. This is enabled by excellent switching FOMs of GaN with R
ON
.Q
G
= 0.9 Ω.nC, and R
ON
.Q
RR
= 11 Ω.nC. The R
th,j-c
is 0.78°C/W which is comparable to packaged GaN-on-Si switches. These results demonstrate that well engineered GaN-on-sapphire technology can be a very competitive platform for the 1200V power device market.