A team from the National Renewable Energy Laboratory (NREL) has shown by modeling that the wafer cost of an emerging Ga₂O₃ wide bandgap semiconductor can be more than 3-times lower compared to SiC. This lower cost of the Ga₂O₃ wafers should lead to less-expensive high-performance power electronic devices in the future.

A paper on their work is published in the journal Joule.

Modeled 6" wafer costs comparison for Ga₂O₃ and SiC wafers, and the Ga₂O₃ cost reduction potential. The Ga₂O₃ cost is >3x less compared to SiC and can be further reduced by better Ir crucible utilization and faster polishing and epitaxy processes. Reese et al.

Power electronics are essential across advanced electrical energy applications including generation, transmission, storage, and utilization of electrical energy. … It is estimated that 30% of all electrical energy passes through power electronics today and this number could reach 80% in the next decade.

Rough estimates using these numbers suggest that even modest loss reductions in present power electronic devices (5% absolute or 50% relative of peak efficiency) can lead to 1.5 quads of energy savings, sufficient to power a third of all homes in the USA. Furthermore, advanced power electronic devices may lower weights and volumes of the systems, thus incentivizing new applications, including alternative transportation and variable frequency drives.

… Power electronic technologies based on [wide bandgap] WBG semiconductors, such as silicon carbide (SiC) and gallium nitride(GaN), can be more efficient than Si due to their much higher breakdown field (E_c) at comparable dielectric constant (ε) and similar charge carrier mobility (μ). These WBG SiC and GaN semiconductors have 100x–1,000x higher figure of merit for power electronics (B_FOM=ε μ E_c³), compared to the narrow-gap Si. … However, one remaining drawback of these WBG semiconductors is the higher cost of the single crystal substrate wafers compared to Si, both due to more complex crystal growth chemistry and the smaller scale of the crystal growth industry.

An emerging alternative WBG power electronic technology based on gallium oxide (Ga₂O₃) has the potential to address this cost performance trade-off by providing lower cost and higher performance compared to established WBG semiconductors.

—Reese et al.

To determine the cost of Ga₂O₃ wafers and compare it to the SiC wafer cost, the NREL team created a bottom-up cost model around a manufacturing process flow.

Modeled steps included crucible charging, crystal growth, ingot machining, wafer processing, and epitaxial growth to approximate fabrication of wafers ready for device fabrication.

Among their findings, they estimated that the >3x cost advantage of Ga₂O₃ compared to SiC wafers could translate to 2x less expensive power electronic devices, assuming a similar device manufacturing process and similar device density on the wafer.

Such significant reductions in cost of WBG power electronic devices could help incentivize widespread adoption of these efficient energy conversion technologies in otherwise cost-sensitive applications, present substantial financial opportunities, and lead to enormous global energy savings, they concluded.

Resources

• Reese et al. (2019) “How Much Will Gallium Oxide Power Electronics Cost?,” Joule doi: 10.1016/ j.joule.2019.01.011