Fraunhofer ISE, a Germany-based solar research institute, and III/V-Reclaim, a German semiconductor recycling company, have developed 150 mm InP-on-GaAs substrates as a cost-effective alternative to conventional indium phosphide wafers. The new substrates have been fabricated using metamorphic buffer layers and chemical-mechanical polishing, which has resulted in low surface roughness and defect densities below 5×10⁶ cm⁻². The wafers are epi-ready and allow direct growth of III-V layers for high-efficiency solar and semiconductor devices. According to III/V-Reclaim, photovoltaic cells fabricated on these wafers have shown voltages comparable to those on standard InP wafers. The technology has already been demonstrated in 4- and 6-inch formats, and scaling to 8 inches is considered feasible. GaAs substrates are mechanically more stable and allow thinner, material-efficient wafers, which has enabled up to 80% cost savings in mass production.