DARPA Awards Contract to Develop Alternative Nitrogen Polar GaN on Sapphire Substrates

Transphorm will explore the use of sapphire substrates to achieve greater cost efficiency for nitrogen polar Gallium Nitride (GaN) solutions compared to conventional gallium polar on silicon carbide solutions By DA Staff / 25 Oct 2021
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Transphorm, Inc. has been awarded a contract by the Defense Advanced Research Projects Agency (DARPA) to explore performance and cost boundaries for manufacturing an alternative Nitrogen polar (N-polar) Gallium Nitride (GaN) solution for U.S. Department of Defense and commercial Radio Frequency (RF)/millimeter wave applications. The contract is worth $0.9 million with a $0.5 million option.

Transphorm will be responsible for delivering the epiwafer technology and sub-contractor, University of California, Santa Barbara (UCSB), will fabricate the RF/mm-wave transistors.

The new project builds on Transphorm’s history as well as ongoing work with the Office of Naval Research (ONR) to establish a domestic resource and supply for RF GaN epiwafers, with emphasis on N-polar GaN, a technology that is proven to deliver greater benefits than today’s more commonly used Gallium polar (Ga-polar) GaN for RF and mm-wave applications. 

Transphorm will explore the use of sapphire substrates to achieve greater cost efficiency for N-polar GaN solutions compared to conventional Ga-polar on Silicon Carbide (SiC) solutions. The work output is expected to yield a stable, high quality thin-epi structure with its capability established by the high-performance transistors.

Transphorm’s team will meet the following program objectives regarding N-polar GaN-on-Sapphire:

  • Establish the overall value proposition
  • Define the high-performance parameter space
  • Define the viability of building the epiwafers

“We’re thankful to DARPA for the opportunity and confidence to further define the N-polar GaN solution for RF applications. This project, coupled with our ongoing work to scale manufacturing with ONR support is an incredible opportunity for Transphorm to grow its position as a premium RF epiwafer supplier, our second business vertical. The goal now is to take that foundation and enable our RF epi customers to achieve more efficient RF power for the dollar,” said Dr. Mishra, CTO and co-founder of Transphorm. 

“Sapphire is an attractive material choice for this purpose but has historically been dismissed as it has low heat conductance. We believe that, with innovative engineering, the program team can overcome that limitation and are excited for the chance to set that benchmark for the GaN RF industry.”

The potential value of N-polar GaN in RF/mm-wave applications as well as possibly for future power electronics is appealing given its efficiencies at frequencies as high as 94 GHz. It is primed to directly benefit DoD systems along with applications for 5G, 6G, and beyond.

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