Researchers create superconducting germanium semiconductor material using standard chip-making techniques - prototype demonstrates millions of superconducting junctions on a 2-inch wafer

Researchers have developed a superconducting germanium semiconductor material by incorporating gallium using standard chip-making techniques. This material transitions to a superconducting state below 3.5 Kelvin and supports dense Josephson junction arrays crucial for quantum and cryogenic RF circuits. The prototype showcases millions of superconducting junctions on a 2-inch wafer, demonstrating practical current densities for device integration. The process involves growing ultra-clean germanium films with gallium dopants using molecular beam epitaxy, enabling a bulk superconducting transition while maintaining an epitaxial interface. This advancement paves the way for scalable wafer-level integration of superconductors on semiconductor-grade substrates, potentially enhancing quantum computing and cryo-RF applications.