Title: Nuclear spin-free 70Ge/28Si70Ge quantum well heterostructures grown on industrial SiGe-buffered wafers Show Chinese title

Title: 无核自旋的70Ge/28Si70Ge量子阱异质结构在工业SiGe缓冲晶圆上生长

Abstract: The coherence of hole spin qubits in germanium planar heterostructures is limited by the hyperfine coupling to the nuclear spin bath due to 29Si and 73Ge isotopes. Thus, removing these nuclear spin-full isotopes is essential to extend the hyperfine-limited coherence times needed to implement robust quantum processors. This work demonstrates the epitaxial growth of device-grade nuclear spin-free 70Ge/28Si70Ge heterostructures on industrial SiGe buffers while minimizing the amounts of highly purified 70GeH4 and 28SiH4 used. The obtained 70Ge/28Si70Ge heterostructures exhibit a dislocation density of 5.3 x 10e6 cm-2 and an isotopic purity exceeding 99.99%, with carbon and oxygen impurities below the detection sensitivity, as revealed by atom probe tomography. Magnetotransport measurements on gated Hall bars demonstrate effective gate control of hole density in nuclear spin-free quantum wells. Negative threshold gate voltages confirm the absence of intentional doping in the wells, while Hall and Shubnikov-de Haas analyses yield consistent carrier densities (1.4 x 10e11 cm-2) and high mobilities (2.4 x 10e5 cm2/Vs). Mobility trends reveal interfacetrap- limited scattering and percolation concentration below 7 x 10e10 cm-2. These analyses, along with atomic-level studies, confirm the high quality of epitaxial 70Ge/28Si70Ge heterostructures and their relevance as a platform for long-coherence spin qubits. Show Chinese abstract

Abstract: 在锗平面异质结构中，空穴自旋量子比特的相干性由于29Si和73Ge同位素对核自旋浴的超精细耦合而受到限制。因此，去除这些含有核自旋的同位素对于延长实现稳健量子处理器所需的超精细限制相干时间至关重要。这项工作展示了在工业级SiGe缓冲层上外延生长器件级的无核自旋70Ge/28Si70Ge异质结构，同时尽量减少使用高纯度的70GeH4和28SiH4。所获得的70Ge/28Si70Ge异质结构表现出5.3 x 10e6 cm-2的位错密度和超过99.99%的同位素纯度，碳和氧杂质低于原子探针断层扫描的检测灵敏度。在栅控霍尔条上的磁输运测量表明，在无核自旋量子阱中实现了有效的栅极控制的空穴密度。负阈值栅极电压证实了阱中没有有意掺杂，而霍尔和舒布尼科夫-德哈斯分析得出一致的载流子密度（1.4 x 10e11 cm-2）和高迁移率（2.4 x 10e5 cm2/Vs）。迁移率趋势显示界面缺陷限制的散射和低于7 x 10e10 cm-2的渗透浓度。这些分析以及原子层面的研究证实了外延生长的70Ge/28Si70Ge异质结构的高质量及其作为长相干自旋量子比特平台的相关性。