Study Shows Sapphire Substrates Dominate GaN Market
Staff -- Semiconductor International, 10/24/2007
With an annual volume of more than 5 millions units of 2 in. equivalent substrates, gallium nitride (GaN)-based green, blue and white LED is the main eater of nitride materials targeting a $3.5B market at the device level, according to a new report from Yole Développement (Lyon, France). Most GaN-based devices are grown on sapphire substrates, with silicon carbide now accounting for ~10% of the total production. The report, titled GaN 2007, is priced at 3,990 Euros.
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The sapphire market for LEDs is now tending toward equilibrium with two-thirds of LEDs manufactured on 2 in., one-third on 3 in. substrates, and a recent introduction of 4 in. production announced by Showa Denko, the report states. The sapphire material market just crossed the $150M barrier in 2006. Silicon carbide (SiC) is entering a 4 in. production stage at Cree (Durham, N.C.).
The report describes the substrate market as partially unstable because of the rapid emergence of new substrates for GaN epitaxy. GaN on silicon, GaN on ZnO, GaN on germanium, GaN on glass, GaN on AlN and composite substrates, such as GaN on diamond or Picogiga International's GaN on silicon on polysilicon carbide (SopSiC), are now pursuing the same goal, which is the best compromise between GaN-quality, large-diameter, low-bowing, high-Tc, controlled-TCE and, of course, low-cost. 6 in. is the main target, now available off-the-shelf from selected companies. That is opening new doors to higher LED productivity toward the gigantic solid-state lighting (SSL) general illumination business.
Picogiga International, a division of the Soitec Group, produces SopSiC designed for low-cost, low-power GaN on silicon and high-cost, high-power SiC for GaN high electron mobility transistor (HEMT) devices.
Alternative GaN substrates will contribute to expand nitride's application fields in power and RF electronics. GaN, as well as SiC, is a wide bandgap material that allows for high breakdown voltages, which makes it suitable for power electronics applications. However, the GaN growth process requires devices to be designed laterally. Lateral devices are limited in terms of breakdown voltage, compared with vertical ones, and become rapidly bulky for high-power-density ranges. This situation deals with a subtle balance between substrate diameter, power density, chip size and device cost. In other terms, GaN power devices on sapphire, silicon or composite substrates can compete with SiC from a cost point of view using larger substrates (4 in.) to compensate the bigger chip size at a given power density.
