Get To Know About The Substrate Challenge Of Gan Substrate

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The need for speed is pushing the industry toward 5G as all manner of devices begin to network. Reduced latency and greater bandwidth promised by the next-generation telecom standard promises. In Frequency bands, many 5G bands reside that are too challenging for traditional semiconductor devices and freestanding GaN substrate based on silicon.


GaN meant for high frequency


Gallium nitride (GaN) is to modern-day and high-frequency applications like RF LDMOS was too early cellular networks. GaN as compared with Si LDMOS and gallium arsenide (GaAs) has long been known to offer benefits that are hard to beat:


• As compared with LDMOS and GaAs, higher breakdown voltage occurs significantly. At over and 0.4 MV/cm for GaAs, 0.2 MV/cm for Si, and 4 MV/cm for GaN, the critical breakdown electric field is estimated. At supply voltages from 28V to 50V, GaN offers ruggedness and high reliability.

• As compared to LDMOS, Electron mobility is higher significantly. Better efficiency and more gain at high frequencies are offered by increased electron mobility.

• GaN ...
... devices from freestanding GaN substrate manufacturer are allowed to operate without complicated or costly structures and with less cooling for heat extraction at High activation energy.

• As a result of better thermal conduction, the size is minimized.

• To linearization techniques like distortion, GaN HEMT characteristics lend themselves well.

• Higher impedances and lower capacitances result from High power density that is easier to match.


Substrate challenge


There are technological challenges, including the difficulty in growing GaN films although the conversion to GaN is well underway. So, for heteroepitaxial growth, another substrate is required.


The substrate material choice is critical. This material must not only have a low lattice mismatch with GaN but also high thermal conductivity.


All requirements are satisfied best by SiC currently while companies have manufactured GaN devices on the diamond, silicon carbide, and Si substrates.


GaN on SiC or GaN on Si


A Closely matching lattice structure is SiC. Thus, with lower dislocation density, GaN epitaxy can be grown on it as compared to other materials. This enhances reliability and minimizes leakage.


On the other hand, Si matches neither thermal properties nor GaN’s lattice structure. This causes higher manufacturability issues and defect densities as well as reliability due to warping. Companies have to use an overall more complicated epitaxial structure and complex buffer layers to overcome these problems.


For realistic drain efficiencies, high power densities are allowed by it to be efficiently dissipated as SiC, and GaN has much better thermal conductivity as compared to Si. The extreme channel temperatures are prevented by this due to self-heating. Moreover, as temperature increases, GaN on Si is susceptible to degraded performance as compared with GaN on SiC. Its resistivity reduces significantly when the Si substrate heats up. Negatively impacting RF performance, a substrate with low resistivity equates to higher RF loss.


Si substrates as compared to SiC substrates also have a higher parasitic capacitance, which results in Si substrates with a more limited bandwidth of operating.


Freestanding GaN Substrate becomes a compelling solution over GaN on Si due to the impact of GaN on SiC devices on the factoring in the higher efficiency, the savings in weight, as well as space, total costs, smaller, die size, and better high-frequency operation.

Xiamen Powerway Advanced Material Co., Limited (PAM-XIAMEN) is a top-class enterprise for compound semiconductor material integrating semiconductor crystal growth, process development, and epitaxy.