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Blog: GaAs or GaN for High-Reliability RF Applications?

Criteria Labs - GaAs vs GaN Blog GraphicPrior to the 1990s, RF devices were commonly developed with Gallium Arsenide (GaAs) technology. At the time RF devices developed with GaAs technology was the best choice for high-reliability and harsh environment applications. Specifically, applications with low noise figure and high-frequency requirements. Beginning in the early 1990s, Gallium Nitride (GaN) gained popularity as the go-to compound for high-frequency RF applications. With enhanced linearity characteristics at higher frequency ranges, RF devices developed with GaN compounds have the capability to transmit signals over very long distances at higher power ranges.

Read on as we compare the two technologies and what factors to consider when developing GaAs or GaN RF devices for high-reliability and harsh environment applications.

 

GaAs and GaN Compound Characteristics

GaAs and GaN compounds are semiconductor materials, each containing two different elements with different structures (pictured below). GaAs and GaN compounds have been found to be particularly useful in high-reliability RF applications. Both compounds have greater electron mobility than silicon, so they are more effective at higher frequency ranges. Also, the two compounds can operate at higher temperatures as compared to silicon.

Gallium Arsenide (GaAs) Structure Blog Graphic

Gallium Arsenide (GaAs) Structure

Gallium Nitride (GaN) Structure Blog Graphic

Gallium Nitride (GaN) Structure

 

 

 

 

 

 

 

 

 

 

During production, the two compounds are developed into ingots (technically known as a “boule”), which are then sliced into thin wafers. GaAs is typically available in wafer form as large as 8 inches in diameter. GaN is commonly available in wafers as large as 4 inches in diameter. While the wafer manufacturing costs associated with GaN is more than GaAs, the end RF device costs are typically lower. This is due in part to smaller device packaging and heat sink costs.

The table below shows a comparison of the physical property characteristics for GaAs and GaN compounds*

Physical Property Eg (eV) ε μn
(cm²/V·s)
Ec
(MV/cm)
Vsat
(10⁷cm/s)
Total
Dislocation (cm²)
Thermal Conductivity
(W/m·K)
GaAs 1.42 13.1 8500 0.4 2 50
GaN 3.44 9 1250 3.3 2.5 >10⁵ 253

 

GaAs and GaN Performance Characteristics

The key performance characteristics of these two semiconductor compounds are linearity, frequency, bandwidth, and power.

Characteristic GaAs GaN
Linearity Moderate Poor
Frequency <250GHz <30GHz
Bandwidth Narrow to Moderate Wide
Power 10 to 20 Watts
Low Power Density
10 to 100’s of Watts
High Power Density

 

When selecting semiconductor compounds, neither GaN nor GaAs is the best option for all applications, but each certainly has its advantages. RF device applications that demand less interference and noise figures with adequate thermal performance tend to gravitate towards GaAs. In high power applications where large amounts of heat is produced, GaN may be the best option. It’s important to note that GaN is more often than not the best option for high-reliability and harsh environment applications where SWaP-c (Size, Weight, Power and Cost) performance is critical.

Conclusion

In conclusion, the best option, mix of components, and system design depends heavily on your individual requirements. With more than 20 years of experience in GaAs and GaN, Criteria Labs has completed hundreds of RF device designs. From mission critical aerospace to harsh environment applications, our end-to-end RF device and engineering solutions are trusted by the largest organizations in the world. Connect with us today and learn how we can help you meet your unique project requirements.

 

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*References:

Sun, Yue & Kang, Xuanwu & Zheng, Yingkui & Lu, Jiang & Tian, Xiaoli & Wu, Hao & Wang, Wenbo & Wei, Ke & Liu, Xinyu & Zhang, Kouchi & Zhang, Guoqi. (2019). Review of the Recent Progress on GaN-Based Vertical Power Schottky Barrier Diodes (SBDs). Electronics. 8. 575. 10.3390/electronics8050575.

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