| Abstract | The concurrent achievement of the record-low resistance charge transport and compatibility with spin qubit technology in solid-state materials is a critical milestone for advancing high-speed, energy-efficient classical and quantum electronics technologies. Here, we demonstrate that holes, the positively charged counterparts of electrons, can propagate with exceptional ease in a nanometres-thin compressively strained germanium layer epitaxially grown on a silicon substrate. Through precise material engineering, we achieve a record-breaking hole mobility of 7.15×10⁶ cm²V⁻¹s⁻¹ at a density of 1.7×10¹¹ cm⁻², establishing a new benchmark for hole transport in group-IV semiconductor materials, importantly, epitaxially grown on a silicon substrate. Our work outlines a design strategy for realising an ultra-clean, low-dimensional system that confines highly mobile holes within a quantum well, while maintaining excellent electrostatic tunability. Crucially, the observed high hole mobility is achieved in gated Hall-bar devices, demonstrating their practical viability for scalable cryogenic classical and quantum electronics applications. These findings unlock new opportunities for a high-performance semiconductor platform capable of underpinning the next generation of quantum information processing, cloud data centres, AI-driven technologies and energy-efficient electronics. |
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