Ultralow 1/f Noise in a Heterostructure of Superconducting Epitaxial Cobalt Disilicide Thin Film on Silicon

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• 作者：Shao-Pin ChiuSheng-Shiuan Yeh ; Chien-Jyun Chiou ; Yi-Chia Chou ; Juhn-Jong Lin ; Chang-Chyi Tsuei
• 刊名：ACS Nano
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：11
• 期：1
• 页码：516-525
• 全文大小：702K
• ISSN：1936-086X

文摘

High-precision resistance noise measurements indicate that the epitaxial CoSi₂/Si heterostructures at 150 and 2 K (slightly above its superconducting transition temperature T_c of 1.54 K) exhibit an unusually low 1/f noise level in the frequency range of 0.008–0.2 Hz. This corresponds to an upper limit of Hooge constant γ ≤ 3 × 10^–6, about 100 times lower than that of single-crystalline aluminum films on SiO₂ capped Si substrates. Supported by high-resolution cross-sectional transmission electron microscopy studies, our analysis reveals that the 1/f noise is dominated by excess interfacial Si atoms and their dimer reconstruction induced fluctuators. Unbonded orbitals (i.e., dangling bonds) on excess Si atoms are intrinsically rare at the epitaxial CoSi₂/Si(100) interface, giving limited trapping–detrapping centers for localized charges. With its excellent normal-state properties, CoSi₂ has been used in silicon-based integrated circuits for decades. The intrinsically low noise properties discovered in this work could be utilized for developing quiet qubits and scalable superconducting circuits for future quantum computing.