News: Suppliers
22 May 2025
Fraunhofer ISE and III/V-Reclaim develop 150mm InP-on-GaAs substrates that can replace prime InP wafers
Together with wafer recycling firm III/V-Reclaim of Pleiskirchen, Germany, the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany has produced high-quality indium phosphide on gallium arsenide substrates (InP-on-GaAs wafers) with up to 150mm diameter. The new wafers can effectively replace classic InP in a variety of applications, offering a scalable pathway to lower cost. The research team developed a new process to deposit a thin layer of high-quality InP on GaAs. Following a special surface treatment, these wafers are delivered epi-ready, enabling customers to directly grow III-V epitaxial structures and manufacture high-performance InP-based semiconductor devices.
“Companies can use our new InP-on-GaAs substrates to manufacture high-efficiency devices,” says Carmine Pellegrino, project manager at Fraunhofer ISE. ”However, it costs much less than InP and there are no limitations in terms of scalability to even 8-inch diameter wafers.”
The application of indium phosphide on gallium arsenide is challenging because defects occur during the growth of the indium phosphide that can degrade the performance of the final device. The researchers were able to avoid this by incorporating a series of metamorphic buffer layers and by subjecting the fully grown InP-on-GaAs wafer to a special chemical-mechanical polishing (CMP) step. After this, the wafers are shiny with very low surface roughness and defect densities below 5x106cm–2.
The researchers tested the material quality and performance of the new InP-on-GaAs wafers and compared them to standard InP substrates. “The results are extremely promising,” says Frank Dimroth, head of the III-V photovoltaics department at Fraunhofer ISE. “Photovoltaic cells fabricated on our engineered wafers achieve open-circuit voltages comparable to reference devices on prime InP wafers. The performance is consistently uniform across the entire 6-inch wafer, enabling reliable, high-yield production.”
As part of a series of experiments, the team has so far produced InP-on-GaAs wafers with diameters of 4-inches and 6-inches, with no obstacles foreseen for a future transition to 8-inches. Classic InP substrates, on the other hand, are currently available in sizes from 2-inches to 4-inches, with a 6-inch version only recently becoming available. This is because GaAs substrates are more robust, and formats with a diameter of up to 8 inches are already well established in the semiconductor industry. The higher stability of GaAs also makes it possible to produce thinner wafers, so less material is used and additional costs can be saved.
“Our technology naturally benefits from having gallium arsenide as a basis,” says Pellegrino. ”The production costs of the new substrates are significantly lower than those of indium phosphide wafers, with a savings potential up to 80% in mass production, according to our first calculations. In addition, our approach bypasses constraints on the supply of indium phosphide.
Fraunhofer ISE inaugurates Center for High Efficiency Solar Cells
