Wide-band-gap semiconductor materials such as gallium nitride (GaN) offer far higher performance than traditional silicon but cost significantly more. However, by 2020 GaN costs will drop enough for it to become competitive based on performance gains, according to a new report from Lux Research: “Price or Performance: Bulk GaN Vies with Silicon for Value in LEDs, Power Electronics and Laser Diodes.”
Bulk GaN is very expensive today, costing about $1,900 or more for a two-inch substrate, compared with $25 to $50 for a far larger six-inch silicon substrate. But GaN materials offer higher efficiencies than silicon, leading to greater energy savings in devices such as power electronics, laser diodes, and light-emitting diodes (LEDs). These gains can offset cost disadvantages, Lux notes—the price-to-performance ratio is the key to adoption.
The future of bulk GaN is going to come down to how it faces off against silicon substrates. Bulk GaN wins in laser diodes and it can become relevant in LEDs and power electronics by boosting yield and performance.—Pallavi Madakasira, lead author
Lux Research analysts broke down the manufacturing costs for ammonothermal and hydride vapor phase epitaxy (HVPE) processes for making bulk GaN, as well as for GaN epitaxy on both silicon and GaN substrates, and determined where the price/performance trade-off will land. Among their findings:
HVPE is the cheaper alternative. Two-inch ammonothermal substrate costs will fall by more than 60% to $730/substrate in 2020. While four-inch HVPE substrate costs will fall by 40% to $1,340/substrate in 2020, the larger size makes it the more economical choice.
Performance boost is key. Bulk GaN can overcome high cost by boosting performance in terms of lumen (lm) output in LEDs or volt-amp (V-A) capacity in power electronics, by allowing the use of smaller dies and providing higher yields. In LEDs, GaN can match silicon with a 380% relative performance—an ambitious but realistic goal. For power electronics, performance at 360% of devices on silicon makes bulk GaN a winner.
New materials on the horizon. Emerging materials such as aluminum nitride (AlN) are ideally suited to very low wavelength, ultra violet-LED, green laser diode and high switching frequency power electronics applications, and can be an effective alternative to bulk GaN.