Phase-coherent superconducting proximity in topological materials requires clean superconductor-topological material (SC-TM) interfaces, yet conventional top-contact fabrication often degrades them through oxidation, polymer residue, and process-induced disorder. Here we introduce a pre-patterned superconducting bottom-contact architecture in which MoRe/Au electrodes are defined before van der Waals crystal transfer, thereby avoiding on-flake lithography after transfer. In WTe2- and Bi1.5Sb0.5Te1.7Se1.3-based Josephson junctions, this architecture yields systematically larger I_c R_N and longer-ranged coupling than conventional top contacts. Cross-sectional STEM/EDS reveals atomically abrupt, chemically well-separated interfaces. These results establish pre-patterned SC-TM contacts as a practical route to reproducible, micrometer-scale Josephson platforms in van der Waals topological materials.
@article{arxiv.2603.23148,
title = {Pre-Patterned Superconducting Contacts for Clean Superconductor-Topological Material Interfaces Enabling Long-Range Josephson Coupling},
author = {Yong-Bin Choi and Chang-Won Choi and Luke Holtzman and Hoil Kim and Seongwoo Kang and Kenji Watanabe and Takashi Taniguchi and James Hone and Jun Sung Kim and Si-Young Choi and Gil-Ho Lee},
journal= {arXiv preprint arXiv:2603.23148},
year = {2026}
}