The past 30 years has witnessed the impressive progress of GaN-based technology in various fields. Today, commercial GaN-based devices are available for both optoelectronic and electronic applications.
In the past, due to technical complexities, limited availability, and the high cost of native bulk GaN substrates, different foreign substrates, including sapphire, SiC and silicon, were used to develop GaN-based devices for various applications. The technology used in commercially available GaN devices is summarized in the following table:
|Technology||GaN on sapphire||GaN on SiC||GaN on Silicon||GaN on GaN|
|LED||RF, LED||Power, LED||Laser diode, LED|
Heteroepitaxial growth on non-native substrates, such as sapphire or SiC, results in higher dislocation density and strains in the GaN epitaxial layers. This is due to the mismatch in crystal constants and coefficients of thermal expansion (CTE) between the GaN epi layer and the non-native substrates, as shown in the following table:
|Lattice mismatch compared to GaN||CTE mismatch compared to GaN|
The dislocations and strains hinder GaN device performance improvement. Both academia and industry are studying using native bulk GaN substrates for high quality GaN-on-GaN devices in parallel with other GaN technology. The progress of GaN substrates – specifically, bigger, better quality and cheaper wafers – sees GaN-on-GaN technology increasingly entering optoelectronic applications. This could extend to electronic applications in the future, as shown in the recent report, “Bulk GaN Substrate Market 2017” from Yole Développement.
(Source: Bulk GaN Substrate Market 2017 report, Yole Développement, Feb. 2017)
The LED market is traditionally dominated by GaN-on-sapphire technology. However, GaN-on-GaN LEDs are beginning to enter niche applications like automotive lighting or spot lighting, led by players like Soraa (US) and Panasonic (JP). GaN-on-GaN LEDs exhibit a significant performance advantage over conventional sapphire-based LEDs. These GaN-on-GaN LED chips can achieve much higher current density and give more freedom for lighting design. This success seems to have revived the interest of other LED manufacturers, who are beginning to seriously consider using GaN substrates for similar LED applications. Yole Développement is expecting new GaN-on-GaN LED players, following in the footsteps of Soraa and Panasonic, to enter the market in coming years. LED applications, even niche ones, will make a large contribution to the growth of the bulk GaN substrate market in the near future.
Bulk GaN Substrate Market 2017
Laser diodes and high-brightness LEDs are driving the bulk GaN substrate market - More information here
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