2D High-Temperature Superconductor Integration in Contact Printed Circuit Boards

Abstract

Inherent properties of superconducting Bi 2 Sr 2 CaCu 2 O 8+x films, such as the high superconducting transition temperature T c , efficient Josephson coupling between neighboring CuO layers, and fast quasiparticle relaxation dynamics, make them a promising platform for advances in quantum computing and communication technologies. However, preserving two-dimensional superconductivity during device fabrication is an outstanding experimental challenge because of the fast degradation of the superconducting properties of two-dimensional flakes when they are exposed to moisture, organic solvents, and heat. Herein, to realize superconducting devices utilizing two-dimensional (2D) superconducting films, we develop a novel fabrication technique relying on the cryogenic dry transfer of printable circuits embedded into a silicon nitride membrane. This approach separates the circuit fabrication stage requiring chemically reactive substances and ionizing physical processes from the creation of the thin superconducting structures. Apart from providing electrical contacts in a single transfer step, the membrane encapsulates the surface of the crystal, shielding it from the environment. The fabricated atomically thin Bi 2 Sr 2 CaCu 2 O 8+x -based devices show a high superconducting transition temperature of T c ≃ 91 K close to that of the bulk crystal and demonstrate stable superconducting properties.

Apparent color and Raman vibrational modes of the high-temperature superconductor Bi2Sr2CaCu2O 8+δ exfoliated flakes

“…We have studied the time evolution of the Raman modes at 116 cm −1 and 460 cm −1 for different flake thickness and no significant changes in these bands can be seen, indicating that the exposure to moisture does not have an impact in the Raman spectra of the BSCCO flakes [26] (see figure S5 in SI). Although the two Raman modes located around 650 cm −1 associated to the oxygen content [57] cannot be tracked in our experiments (due to superposition with the substrate peaks), it is reasonable to expect that superconductivity remains inside the flakes surrounded by underdoped/amorphous layers at the surface [13,25].…”

“…As mentioned in the Introduction, when exposed to air or even a controlled gas atmosphere, BSCCO-2212 flakes lose oxygen dopant content [13] and an amorphous superficial layer is formed [25]. We have characterized the apparent colors of flakes inside and outside a N 2 glove-box to check if there were changes in tonalities due to ambient exposure and thus in the optical properties of the material.…”

“…Although it is a promising material that can be used to create innovative devices, only a few works [21,22] have studied BSCCO-2212 exfoliated flakes in depth due to the difficulty in its manipulation. Exposure of the flakes to ambient conditions, moisture and even in a controlled glove-box atmosphere can change the oxygen content, δ, and degrade the crystallinity of a superficial layer destroying the metallic-superconducting response rendering the surface insulating [13,[22][23][24][25][26]. In this sense, BSCCO-2212 must be carefully prepared in controlled inert atmospheres or even using liquid nitrogen cooled stages, to avoid a complete degradation of the sample [14,18], making especially difficult to perform fundamental studies and to integrate it with other commonly used 2D materials.…”