掩埋硅层捕获氧杂质实现Si/SiGe量子阱的迁移率提升
Mobility Enhancement in Si/SiGe Quantum Well Enabled by a Buried Si Layer Trapping Oxygen Impurities
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中文总结 AI 辅助
研究针对Si/SiGe量子器件材料中氧杂质限制迁移率的问题，通过在SiGe势垒中引入掩埋Si层，使氧含量降低约5倍，提升电子迁移率，为异质结构设计提供了工艺兼容的解决方案。
中文摘要 AI 辅助
降低未掺杂Si/SiGe场效应异质结构中的无序性仍是可扩展量子器件（尤其是电子自旋量子比特）面临的重要材料挑战。氧等背景杂质已被证实会限制迁移率，但抑制其掺入的实用异质结构设计策略仍未得到充分探索，且其在不同输运机制中的影响也未完全明确。本文展示了一种通过在下部SiGe势垒中引入薄的电惰性掩埋硅层，在200mm Si(100)衬底上采用减压化学气相沉积（RP-CVD）生长的Si/SiGe量子阱异质结构中实现氧含量降低和迁移率提升的简单方法。二次离子质谱显示，该掩埋硅层可重复性地将后续生长的SiGe中的氧背景含量降低约5倍，且不改变活性量子阱区域。与密度和温度相关的磁输运测量进一步表明，这种氧含量降低提升了电子迁移率，同时未显著改变渗流密度和与密度相关的迁移率标度。冷却至0.3K时，高氧和低氧器件均表现出相似的与密度相关的分数迁移率提升，表明降低的氧背景改善了动量弛豫，且未显著改变主导的低密度无序环境。这些结果确立了掩埋硅层作为一种简单且工艺兼容的异质结构设计元件，可用于减少200mm CVD生长的Si/SiGe量子器件材料中的氧掺入并改善其输运性能。
英文摘要
Reducing disorder in undoped Si/SiGe field-effect heterostructures remains an important materials challenge for scalable quantum devices, particularly electron spin qubits. Background impurities such as oxygen have been identified as mobility-limiting, yet practical heterostructure-design strategies for suppressing their incorporation remain underexplored, and their influence across different transport regimes is not fully established. Here, we demonstrate a simple route to oxygen reduction and mobility enhancement in Si/SiGe quantum-well heterostructures grown by reduced-pressure chemical vapor deposition (RP-CVD) on 200 mm Si(100) substrates through the introduction of a thin, electrically passive buried Si layer within the lower SiGe barrier. Secondary-ion mass spectrometry shows that the buried Si layer reproducibly reduces the oxygen background in the subsequently grown SiGe by approximately a factor of five, without modifying the active quantum-well region. Density- and temperature-dependent magnetotransport measurements further show that this reduction increases the electron mobility, while leaving the percolation density and density-dependent mobility scaling largely unchanged. Upon cooling to 0.3 K, both high- and low-oxygen devices exhibit similar density-dependent fractional mobility enhancements, indicating that the reduced oxygen background improves momentum relaxation without substantially altering the dominant low-density disorder landscape. These results establish the buried Si layer as a straightforward and process-compatible heterostructure-design element for reducing oxygen incorporation and improving transport in 200 mm CVD-grown Si/SiGe quantum-device materials.
发表机构
- IHP - Leibniz Institute for High Performance Microelectronics（IHP - 莱布尼茨高性能微电子研究所）
- Dipartimento di Scienze, Università Roma Tre（罗马第三大学科学系）
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