Fraunhofer ISE researchers say their newly fabricated gallium arsenide substrates (InP-on-GaAs wafers) can replace prime indium phosphide wafers and offer a scalable pathway to lower costs.
Patrick Jowett
Image: Fraunhofer ISE
Scientists at the Fraunhofer Institute for Solar Energy Systems ISE have produced indium phosphide on InP-on-GaAs wafers up to 150 mm in diameter.
Working in collaboration with German semiconductor specialists III/V-Reclaim, the team developed a process to deposit a thin layer of high-quality indium phosphide on gallium arsenide.
The team said the application is challenging because defects occur during the growth of the indium phosphide, which can degrade the performance of the final device. To avoid such defects, the team incorporated a series of so-called ‘metamorphic buffer layers’ and by subjecting the fully grown InP-on-GaAs wafer to a special chemical-mechanical polishing step.
Following the surface treatment, the wafers are shiny and feature very low surface roughness and defect densities below 5*106 cm-2. Fraunhofer ISE said in a statement that their new wafers can “effectively replace classic indium phosphide in a variety of applications, offering a scalable pathway to lower cost.”
Carmine Pellegrino, project manager at Fraunhofer ISE, said companies can use the InP-on-GaAs substrates to manufacture high-efficiency devices.
“However, it costs much less than InP and there are no limitations in terms of scalability to even 8-inch diameter wafers,” added Pellegrino.
The research team have tested the material quality and performance of the wafers against standard indium phosphide substrates and say the results have been “extremely promising.”
“Photovoltaic cells fabricated on our engineered wafers achieve open-circuit voltages comparable to reference devices on prime InP wafers,” Pellegrino said. “The performance is consistently uniform across the entire 6-inch wafer, enabling reliable, high-yield production.”
Pellegrino noted that the production costs of the new substrates are significantly lower than those of indium phosphide wafers, with potential savings potential up to 80% in mass production.
“In addition, our approach bypasses constraints on the supply of indium phosphide,” said Pellegrino.
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