Chemically Synthesized Single-Crystalline Gold Flakes for Patternable van der Waals Contacts

Unlocking the full potential of two-dimensional (2D) electronics demands patternable electrical contacts that simultaneously offer atomic flatness, high conductivity, and robust resistance against thermal and environmental degradation. Here, we demonstrate that chemically synthesized, single-crystalline gold flakes meet all these requirements. Notably, the gold flakes can be precisely patterned into desired geometries via cysteamine-assisted mild wet etching, distinguishing them from other 2D metallic materials. By integrating gold flakes into field effect transistors (FETs) with a monolayer MoS2 channel, we achieved a low Schottky barrier height of ∼23 meV. Furthermore, we revealed that their unique flexibility enabled conformal contacts on thick quasi-2D AuxPd1-xTe2 (x = 0.33) crystals with a thickness of hundreds of nanometers, facilitating the precise measurement of superconductivity in this quantum material. This work establishes single-crystalline gold flakes as ideal metallic 2D building blocks for advancing next-generation logic and quantum devices.