Optimizing AlN/GaN Transistors: The Role of AlGaN Back-Barrier Layers and Carbon-Doped Buffers

What is it about?

This study investigates the physical mechanisms underlying carbon-doped buffer and AlGaN back-barrier layer in state-of-the-art millimeter-wave AlN/GaN transistors. The impact of carbon doping, Al mole fraction, and channel thickness on device performance was analyzed. The results indicate that a 150 nm undoped GaN channel and a highly carbon-doped GaN buffer lead to good electron confinement, but high current collapse. On the other hand, a 25% Al mole fraction in the AlGaN back barrier layer, combined with a 150 nm undoped GaN channel, provides excellent electron confinement and low current collapse. This study demonstrates that careful engineering of carbon concentration and channel thickness is crucial for achieving robust devices with high performance under short gate lengths.

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Why is it important?

The research is important because it investigates the physical mechanisms underlying carbon-doped buffer combined with an AlGaN back-barrier layer in state-of-the-art millimeter-wave AlN/GaN transistors. This study helps engineers to understand how to achieve high device performance with superior voltage operation while using short gate lengths. The findings can contribute to the development of high-frequency power applications, such as radio frequency (RF) power amplifiers, radar systems, and satellite communications. Key Takeaways: 1. The research investigates the impact of the Al mole fraction into the back-barrier, carbon doping in the buffer, and channel thickness on device performance. 2. A 150 nm undoped GaN channel followed by a highly carbon-doped GaN buffer results in good electron confinement but high current collapse. 3. An Al mole fraction of 25% in the AlGaN back barrier layer combined with a 150 nm undoped GaN channel provides excellent electron confinement and low current collapse. 4. Electric field penetration inside the GaN buffer is prevented due to strong polarization from the back barrier when the Al-content is high enough, leading to superior electron confinement. 5. Careful engineering of the carbon concentration together with the undoped GaN channel thickness is crucial to achieve robust devices with high device performance.