Silicon carbide (SiC) is an important material for the whole electronic sector. It provides stability at high temperatures and is therefore, widely applied in electric vehicles, space aviation devices, and industrial machinery. SiC wafers have incredible thermal conductivity, top voltage operation, and fewer switching losses than their silicon counterparts. Consegic Business Intelligence analyzes that SiC Power Semiconductor Market size is estimated to reach over USD 7,622.77 Million by 2031 from a value of USD 987.85 Million in 2022 and USD 1,219.26 Million in 2023, growing at a CAGR of 25.7% from 2023 to 2031.Nevertheless, SiC wafers are also met with challenges due to the fact that they are fragile in processing, in the course of their operation, they are sensitive to high temperatures. This includes Denuded Zone Generation (DZG), crystallographic sloppiness, and the complexity of doping, which spoil the wafer’s total performance under high-temperature conditions.As a result of these limitations, researchers and practitioners are eager to find a more viable high-temperature-tolerant material. They put a special emphasis on examining both the material and technology that can substitute SiC or be complementary to it.
Challenges of High-Temperature SiC Wafer Fabrication
Silicon carbide wafers are among the main examples of improper processes in their production. Indeed, the high-temperature processes like annealing or epitaxial growth make them susceptible to several defects that can be either micropipes, dislocations, or suitable solutions. The resulting faults do not only interrupt the normal operation of the wafer due to its jeopardy but also cause it to lose its electrical characteristics. Besides, the flooding of SiC with nitrogen or aluminum-like materials at high temperatures is often associated with non-homogeneous dopant distribution affecting the effectiveness of components such as MOSFETs and Schottky diodes.In addition, the issue of thermal instability during device operation cannot be ignored. Even though SiC is stated to survive by 600°C theoretically for a long time exposure to such conditions, can cause material degradation and reliability problems in the devices. The high cost and complicated procedure of high-quality SiC wafers, tempered by such a challenge as the external temperature sensitivity, also specify the necessity of novel materials.
Alternative Materials to SiC for High-Temperature Applications
- Gallium Nitride (GaN)
Gallium Nitride (GaN) has gained considerable amounts of attention as a potential alternative to SiC, especially in high-power and high-frequency applications. GaN is superior in several aspects, including a decent gap (3.4 eV) that resembles the SiC and higher electron mobility interactions that enable higher frequency charges. When it comes to thermal performance, GaN can function proficiently at high temperatures, its thermal conductivity (130 W/m·K) is but a part of SiC (370 W/m·K), it is even less so that it can be used in such extreme heat environments. The main gold ball of GaN, however, is the possibility to be made on silicon substrates, which reduces expenses drastically compared to SiC wafers. On the other hand, GaN-on-Si substrates can also be used by a few companies to put GaN devices along with silicon-based semiconductor technologies, this saves time and money that come with the production of power electronics and RF devices. The reason GaN is included in high-voltage circuits and still works efficiently in circumstances where temperatures are around 250°C is that GaN can deal with high voltages and temperatures at which it does not happen, it is a good alternative for moderate high-temperature applications.
- Diamond
Diamond has been marked as a really promising material for the utilization of very high temperatures and power, given its incredible thermal conductivity (2200 W/m·K), it is one of the most suitable materials for extreme high-temperature and high-power applications. The wide bandgap (5.5 eV) of diamond is way bigger than SiC and GaN’s and it is working at even higher volts and higher temperatures theoretically. Diamond also has the feature of very high heat dissipation, which makes it perfect for the environments that need thermal management the most.On the other hand, diamond-semiconductors are still in the prototype stage, waferscale synthesis, doping, and device fabrication being the biggest obstacles to commercial sourcing. Current studies focus on the growth of diamond films by chemical vapor deposition (CVD) on a substrate, but it still lacks scalability. Regardless of that, for very specific high-temperature, high-power applications like radar systems, and deep-space exploration, diamond still stays on the list as a very promising candidate for the future.
- Gallium Oxide (Ga2O3)
Gallium Oxide (Ga2O3) is an exceptional ultra-wide bandgap semiconductor (4.8 eV) solid that has exhibited possibilities for use in high-temperature and high-voltage devices. Ga2O3 can be utilized to boost higher breakdown voltages than SiC and GaN, thus it can be used in power electronic devices that need to operate in extremely harsh environments. In addition, Ga2O3 can be grown using melt-based processes that are cheaper and more scalable than SiC’s sublimation growth techniques.Nevertheless, the primary hindrance to the application of Ga2O3 lies in its relatively low thermal conductivity (~27 W/m·K). This, indeed, is a challenging problem that has been raised recently, especially in high-power devices where the dissipation of heat is crucial. Current research is being carried out to enhance the thermal behavior of the material with the help of proper device architecture, and even coupling with other materials to quelch dissipation.
- Aluminum Nitride (AlN)
Aluminum Nitride (AlN) is another wide bandgap material (6.2 eV) is another material that is being tested as an alternative to SiC for high-temperature applications. AlN has excellent thermal conductivity (285 W/m·K) and can withstand temperatures up to 1000°C. In addition, AlN’s lattice structure is compatible with GaN, allowing for heterostructures that combine the best properties of both materials.But AlN will still require lower cost and more quantity. However, the production cost of the quality AlN wafer is still expensive and its electrical behavior is not as well-study and developed as those for SiC or GaN. Despite these challenges, AlN remains an exciting option in the field of both high-temperature and high-frequency applications, especially in RF and optoelectronic devices.
Conclusion
Despite SiC still being the most commonly used material in high-temperature and high-power electronic applications, it is very sensitive to high temperatures during fabrication and operation hence the demand to find alternatives. Materials such as GaN, diamond, Ga2O3, and AlN offer promising solutions, each with unique properties that can solve the problems faced by SiC wafers. Hence, with the continuous improvement in research and development, these materials may not only be a more cost-effective answer but also more reliable and thermally stable ones for the next generation of power electronics, thus making them an ideal candidate for use in high-temperature environments.
Author Bio: I’m Saurabh, a content writer currently immersed in the vibrant materials and chemicals industry at Consegic Business Intelligence. With over 3 years of professional experience, I’ve specialized as a ghostwriter for prominent companies and industry publications, exploring various topics.
