Pre-Amorphization Implantation (PAI) process for Gallium Nitride (GaN) technology
“My thesis focused on developing a new building block for GaN contact technology. PAI processes are already used for silicon contact technologies in order to improve the thermal stability of the contact layers and to tune the related alloy properties. Our goal was to apply this technology to GaN materials,” explains Laurent Xu. “At the end of my dual master’s degree, I did an internship at CEA-Leti and was offered the opportunity to continue on with this thesis!”
Contacts are an essential building block in a microchip. They are the connectors that enable components to communicate between each other. As a result, their efficiency and cost are important factors in the overall value chain. GaN was initially developed for optoelectronics, but in recent decades, it has been gaining traction in the field of high power/high frequency applications. “As compared to silicon, GaN’s physical properties include a larger band gap and a higher critical electric field. These two characteristics mean we can achieve a transistor with higher power density, which results in a smaller volume and better efficiency,” adds Laurent.
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Doing a thesis is challenging in more ways than one, and having a good support system is essential"
After his internship, Laurent was quick to accept a PhD opportunity: “I knew that CEA-Leti and LTM offered access to top-notch equipment, and during my internship, I was also able to appreciate the strong support of colleagues and experts. Doing a thesis is challenging in more ways than one, and having a good support system is essential.”
Building on the know-how and ecosystem of CEA-Leti and LTM research, Laurent was able to develop a new process for GaN contacts known as Pre-Amorphization Implantation (PAI). “This technology enables us to modify the surface of GaN to increase its reactivity to the metals we layer on top. As a result, we’re able to respect thermal budget restrictions imposed by integration constraints, and occasionally, we can create alloys that shouldn’t be possible otherwise for a given thermal budget. It’s the first time PAI technology has been applied to GaN and the results are very promising.”