Ultralow 1/f Noise in a Heterostructure of Superconducting Epitaxial Cobalt Disilicide Thin Film on Silicon.
basic_science · Level V
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- Record sourced from PubMed, PMID 28027434.
- Also identified by DOI 10.1021/acsnano.6b06553.
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Abstract
High-precision resistance noise measurements indicate that the epitaxial CoSi<sub>2</sub>/Si heterostructures at 150 and 2 K (slightly above its superconducting transition temperature T<sub>c</sub> 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<sup>-6</sup>, about 100 times lower than that of single-crystalline aluminum films on SiO<sub>2</sub> 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 CoSi<sub>2</sub>/Si(100) interface, giving limited trapping-detrapping centers for localized charges. With its excellent normal-state properties, CoSi<sub>2</sub> 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.