Eta Research demonstrates 4 inch semi-insulating free-standing GaN substrates production

Free-standing GaN wafers have the potential impact on improving the performance of GaN-based devices including LEDs, laser diodes, power electronics, and RF devices because of its lattice and thermal expansion matching for homoepitaxial structures. GaN may be the ideal choice of substrates for most GaN-based devices compared to heteroepitaxial substrates.

Semi-insulating GaN wafers may be used to fabricate lateral conducting devices such as high electron mobility transistors (HEMTs). The main interest in semi-insulating GaN wafers is for HEMTs used for RF devices. Compared to GaN on SiC HEMTs, GaN on GaN HEMTs can be grown with a much lower dislocation density in the buffer layer and through the active region. The improvement in crystal quality is expected to increase the 2D electron gas mobility and reduce current collapse. GaN substrates may play a critical role in driving up the power output and power added efficiency of the next generation of RF HEMTs, especially as the operating frequency is pushed beyond the limits of GaN on SiC capability. These GaN on GaN RF devices would be used in markets that many countries view as of national strategic interest, such as satellite communications, 5G and 6G telecommunications, and military application.

Eta Research manufactures and sells 4 inch free-standing GaN wafers, which are available in semi-insulating and n-type conductivity. The resistivity of semi-insulating GaN wafers is higher than 1E9 ohm-cm. The dislocation density is lower than 1E6 cm-2, typically 5E5 to 7E5 cm-2. The radius can be more than 30 m. The roughness of polished GaN wafers surface is less than 0.3 nm, which can be used for epitaxy growth directly. 


Fig. 1 4 inch semi-insulating GaN wafer 


Fig.2 AFM image of GaN polished surface

Eta Research is also able to offer MOCVD GaN HEMTs grown on semi-insulating GaN wafers. Device structures can also be grown with multiple layers including InGaN, AlGaN, n-type doping, and p-type doping. Other potential device structures include LEDs, lasers diodes, and vertical GaN power devices grown on n-type GaN wafers.


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