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

作者：Chiu Shao Pin; Yeh Sheng Shiuan; Chiou Chien Jyun; Chou Yi Chia; Lin Juhn Jong; Tsuei Chang Chyi

来源：ACS Nano, 2017, 11(1): 516-525.

DOI：10.1021/acsnano.6b06553

• superconducting silicide/silicon heterostructure
• interfacial dynamic defects
• 1/f resistance noise
• dimer reconstruction
• two-level-system fluctuators

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 gamma <= 3 X 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.

• 出版日期2017-1