October 31, 2005 – Oki Electric Industry Co. has developed a technique to fabricate transistors of gallium nitride (GaN) on silicon wafers instead of expensive silicon carbide, reports the Nikkei English News. Using this technique, Oki said it can manufacture chips with an output of around 100W for less than half the conventional cost.
GaN-HEMTs (high-electron-mobility transistors) have good signal amplification properties for designing amplification circuits with fewer steps. This can help reduce both the space and the power consumption of multichannel wireless communications systems.
The problem is that GaN and silicon have incompatible crystal structures, so the transistors are now made on substrates of silicon carbide, which cost 50-100 times as much as regular silicon wafers. Oki solved the crystal incompatibility problem by placing intermediate layers of aluminum and gallium-aluminum nitride between the silicon wafer and the GaN layer on which the HEMT transistor gates are fabricated.
The company is considering using the chips for 3G (third-generation) wireless phone base stations and the next-generation WiMAX technology for wide area high-speed wireless data communications.