Field Effect Transistor for High Power Millimeter-Wave Applications

Transistor structure with high breakdown voltage at high frequency operation

The Need

A new generation of high throughput, efficient communication networks and sensors can be enabled through the use of millimeter scale wave regimes. However, current semiconductor materials (such as AlGaN/GaN) have a reduction in breakdown voltage as operating frequency increases, which leads to low power densities at high frequencies. A sharp peak electric field forms at gate edge and causes the device to break down. There is a need for improved semiconductor materials for use in millimeter wave regime devices that addresses these issues.

The Technology

Researchers at The Ohio State University, led by Dr. Siddharth Rajan, have developed a structure that improves the function of millimeter wave regime devices. The structure utilizes ultrahigh dielectric constant material and high electron mobility material that enable high breakdown voltage at high operating frequency. The material also enables high signal gain due to its ability to achieve high transconductance. Finally, this structure provides unique opportunities for heterostructure design, and could have the potential to exceed the performance of the state-of-art technology in the mm-wave and THz frequency regimes.

Commercial Applications

  • Millimeter wave technologies
  • Communication networks
  • Communication sensors
  • Radio astronomy
  • Weapons systems
  • Security screening


  • Much higher breakdown voltage than state-of-the-art GaN HEMT with the same charge density
  • Ability for extreme scaling of the gate to channel distance, enabling very low output conductance and high transconductance
  • Material cost on par with conventional state-of-the-art AlGaN/GaN HEMTs

Research Interests

Dr. Rajan’s education and research activities focus on the area of semiconductor materials and devices. As the head of the Electron Device Laboratory at Ohio State, he adopts a vertically integrated approach combining semiconductor and solid-state physics, material growth, and device engineering.

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