Abstract

Vertical integration of superconducting electronics requires fabrication strategies that preserve pristine interfaces while accommodating oxidation-sensitive elemental superconductors. Here, a freestanding van der Waals membrane architecture enables deposition-based fabrication of vertical Josephson junctions through double-sided processing of a single suspended two-dimensional layer. Using multilayer graphene suspended across lithographically defined through-holes in a SiNx membrane, the work realizes vertical Nb/multilayer graphene/Nb Josephson junctions without ambient exposure of buried interfaces. The devices exhibit clear Josephson coupling, reproducible supercurrents, short-junction-like temperature dependence of the critical current, magnetic interference patterns governed by the aperture geometry, and sub-gap features consistent with a BCS-like superconducting gap.

Abstract

Vertical integration of superconducting electronics requires fabrication strategies that preserve pristine interfaces while accommodating oxidation-sensitive elemental superconductors. Here, a freestanding van der Waals membrane architecture enables deposition-based fabrication of vertical Josephson junctions through double-sided processing of a single suspended two-dimensional layer. Using multilayer graphene suspended across lithographically defined through-holes in a SiNx membrane, the work realizes vertical Nb/multilayer graphene/Nb Josephson junctions without ambient exposure of buried interfaces. The devices exhibit clear Josephson coupling, reproducible supercurrents, short-junction-like temperature dependence of the critical current, magnetic interference patterns governed by the aperture geometry, and sub-gap features consistent with a BCS-like superconducting gap.

Abstract

Vertical integration of superconducting electronics requires fabrication strategies that preserve pristine interfaces while accommodating oxidation-sensitive elemental superconductors. Here, a freestanding van der Waals membrane architecture enables deposition-based fabrication of vertical Josephson junctions through double-sided processing of a single suspended two-dimensional layer. Using multilayer graphene suspended across lithographically defined through-holes in a SiNx membrane, the work realizes vertical Nb/multilayer graphene/Nb Josephson junctions without ambient exposure of buried interfaces. The devices exhibit clear Josephson coupling, reproducible supercurrents, short-junction-like temperature dependence of the critical current, magnetic interference patterns governed by the aperture geometry, and sub-gap features consistent with a BCS-like superconducting gap.

Abstract

Vertical integration of superconducting electronics requires fabrication strategies that preserve pristine interfaces while accommodating oxidation-sensitive elemental superconductors. Here, a freestanding van der Waals membrane architecture enables deposition-based fabrication of vertical Josephson junctions through double-sided processing of a single suspended two-dimensional layer. Using multilayer graphene suspended across lithographically defined through-holes in a SiNx membrane, the work realizes vertical Nb/multilayer graphene/Nb Josephson junctions without ambient exposure of buried interfaces. The devices exhibit clear Josephson coupling, reproducible supercurrents, short-junction-like temperature dependence of the critical current, magnetic interference patterns governed by the aperture geometry, and sub-gap features consistent with a BCS-like superconducting gap.