Regarding GaN devices, these issues should be paid attention to!

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Regarding GaN devices, these issues should be paid attention to! [Copy link]

Regarding GaN devices, you should pay attention to these issues! GaN has advantages, but there are practical considerations for GaN technology in system applications. Therefore, you need to consider the reliability and failure modes of GaN technology deployment, as well as the thermal design of GaN management.

Reliability and failure modes of GaN

At the edge of the gate near the drain, the GaN FET has to withstand a high electric field. If the FET is not designed properly, the additional stress on the barrier layer caused by the reverse piezoelectric effect may cause device cracking and degradation. Figure 3-1 shows a GaN FET with source and drain, and voltage applied to the gate. Figure 3-2 shows the degradation of material structure performance caused by the reverse piezoelectric effect.

To reduce and eliminate the intrinsic failure mode of GaN transistors, technicians need to properly design the structure and thickness of the semiconductor barrier layer to increase the strength of the semiconductor surface. If designed properly, this failure mode can be eliminated.

Managing Thermal Design Challenges

As technology migrates to high power density FET technology, the issue of device temperature management is also increasing. It is important to keep the device "cool" because high temperatures cause degradation of the device's original performance and reliability. In theory, GaN can provide power densities in excess of 20W/mm at relatively high frequencies. However, in practice, the use of GaN is limited to less than 5 W/mm due to high temperatures caused by the large amount of heat dissipation in a very compact space.

Thermal design challenges are the ultimate reason why SiC is the substrate material of choice for high-performance RF applications. The thermal conductivity of SiC is just as important as the high RF power of GaN.

To manage thermal design today, circuit designers spread the heat across the semiconductor surface, increase the distance between device elements, or shrink the device elements. However, thermal design is not just about the chip level. Package engineers must help, too, because the heat flux at the chip-package interface is also high. To ensure that GaN devices can deliver maximum RF power density, a good thermal interface between the chip and the package is extremely important.

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