Understanding Degradation in GaN and SiC Semiconductors: A Comprehensive Study of Stress-Induced Reliability Challenges

These days, semiconductor devices aren’t just in our phones or computers—they’re in everything, from medical equipment to cars and communication systems. With so much riding on these tiny chips, there’s a huge push to make sure they work reliably, no matter what. Gallium nitride (GaN) and silicon carbide (SiC) are two materials that are becoming favorites in these areas because they can handle high power and heat way better than traditional materials. But here’s the problem: even though GaN and SiC are tough, keeping them reliable in real-life, high-stress environments isn’t easy. Even minor wear and tear can snowball into big issues, which isn’t ideal when we’re talking about devices that might be powering essential systems. As tech keeps advancing, we’re asking a lot more from these chips. They’re getting smaller, faster, and more complex, which unfortunately also makes them more delicate. In high-power situations, these chips often deal with extreme voltage and heat, and over time, that can break them down. For example, high electric fields can wear out parts of the chip that are supposed to control current, and constant heating and cooling can cause layers inside the chip to crack or shift. If we want devices that can keep going without failing, we have to figure out what’s causing these issues and find ways to stop them. Two main issues are causing headaches for engineers. First, there’s something called electromigration, which is a fancy way of saying that high currents can make atoms inside the chip’s metal connections drift out of place. Over time, this can cause the connections to fail completely. Then there’s thermal fatigue: when chips are constantly heating up and cooling down, small cracks start forming, and these cracks slowly weaken the whole structure. Things like humidity and contamination make all of this even worse, speeding up corrosion and weakening the chip’s defenses. We’ve got solid standards for traditional silicon-based chips, but those don’t apply well to newer materials like GaN and SiC, which act differently under stress.

To get a clearer picture of what’s going on, researchers Ms. Xiujuan Huang, Professor  Chunsheng Guo, Ms. Qian Wen, Professor Shiwei Feng, and Professor Yamin Zhang from Beijing University of Technology dug into these issues. Their study, published in Microelectronics Journal, is all about how GaN and SiC chips hold up under the kinds of stress they’d face in real life. They ran experiments in the lab and used computer models to see exactly how and where these materials start to break down. Their goal? To create a guide for manufacturers so they can make stronger, more reliable chips. What they found could help improve the design of these chips, making them last longer and perform better in the challenging environments where they’re needed most power. A lot of today’s advanced tech, start to wear down, especially when pushed to their limits. They designed experiments to mimic the real-world conditions these materials face, exposing them to extreme heat, strong electric fields, and cycles of heating and cooling. Through these tests, they monitored things like changes in voltage, unexpected current leaks, and how easily electrons moved through the material. Each finding gave them a window into how these materials degrade[1].

One major takeaway was how constant heat affects GaN and SiC differently. GaN is known for handling high temperatures, but the team saw that, over time, high heat still took a toll. It caused the electrons to scatter more, slowing down the material’s efficiency. SiC was more stable in hot conditions, but it wasn’t entirely immune either. Long exposure led to small mismatches in how the layers expanded, eventually causing tiny fractures. So, while both materials outperform traditional silicon under heat, they still need careful design tweaks to manage the stress of constant high temperatures. They also tested how GaN and SiC hold up under strong electrical stress by applying high voltage fields over time. With GaN, they noticed that the voltage threshold began to shift, showing that defects were slowly building up due to the prolonged voltage. This change means the material’s ability to control current starts to weaken, which could impact its reliability in high-power settings. Another issue they found was “hot carrier injection,” where high-energy electrons got lodged in the material, creating extra heat and defects. These findings pointed out a weakness in GaN’s structure when under long-term electrical stress and suggested a need for design adjustments to help reduce this degradation[2].

They looked closely at how these materials handle physical stress, which is critical since they’re used in environments like automotive and aerospace where devices face constant vibrations and temperature shifts. The tests showed that repeated cycles of heating and cooling, along with vibrations, wore down critical areas like solder joints and interconnects—key points for keeping the device’s electrical flow steady. This wear was especially concerning in high-power devices that carry a lot of current, as constant stress could eventually cause the entire circuit to fail. So, while GaN and SiC are robust under high heat and electricity, they’re still vulnerable to mechanical stress from their setup and mounting.

Gate oxides, the thin layers that help control current flow in these devices, were also a focus[3]. These insulating layers are crucial but can break down under constant high voltage. The authors found that GaN and SiC gate oxides were more resilient than traditional silicon, with much higher failure thresholds. However, they still began to show signs of breakdown after prolonged exposure, leading to increased current leakage that could compromise the device. This confirmed that while GaN and SiC offer better gate oxide durability, further improvements are necessary to ensure they can handle high-voltage applications over long periods. Lastly, they investigated how environmental factors like humidity and contamination affect these materials. When exposed to high-humidity conditions, the devices quickly showed signs of corrosion, especially in the metal connections. Contaminants like metal ions, even in small amounts, managed to embed themselves in the semiconductor, disrupting its performance. This highlighted the need for protective measures, such as coatings, to keep these devices stable in challenging environments[4].

We think the new study takes a deep dive into understanding how durable advanced materials like GaN and SiC actually are when they’re put through the stresses of real-world use. These materials are getting a lot of attention because they can handle high power and high-frequency demands, which makes them great for everything from high-performance electronics to specialized applications in fields like aerospace and automotive. But the big question is, how well do they hold up over time, especially in tough environments? This research helps answer that by showing how GaN and SiC respond to things like heat, electrical strain, physical stress, and environmental exposure, offering a clearer look at what keeps them going and what eventually causes them to wear down. In conclusion, the findings of Professor Yamin Zhang and colleagues are pretty significant, especially for industries that need electronics to be ultra-reliable and resilient. By understanding the specific ways GaN and SiC can degrade—whether it’s GaN experiencing voltage shifts under constant high electrical stress or SiC developing micro-cracks from repeated heating and cooling—manufacturers can start designing devices that not only tap into the strengths of these materials but also guard against their weak points. This could lead to a shift in how devices are built, with designs that are more focused on making the most of GaN and SiC while extending their useful life. It’s a big deal because, in the end, more durable devices mean fewer repairs, lower maintenance costs, and better performance, especially in demanding applications. The study also highlights something critical: how environmental factors like humidity and contamination can speed up material breakdown, even in durable materials like GaN and SiC. To counter this, the research suggests we need to think about better protective packaging—like advanced coatings or cases that keep out moisture and other contaminants. This is especially important for devices that have to operate in harsh conditions. Plus, the study points out the need for ongoing research into better materials for gate oxides (the thin layers that help manage current), which could help GaN and SiC perform even better under high voltage over long periods.