Via Method for Lithography Free Contact and Preservation of 2D Materials

TL;DR

This paper introduces a lithography-free via contact method for 2D materials, enabling robust electrical contacts and long-term preservation of air-sensitive 2D materials, facilitating advanced multi-layer heterostructures.

Contribution

A novel via contact technique that avoids lithography on 2D materials, protecting air-sensitive layers and enabling complex heterostructures.

Findings

Contacts remain stable for months without degradation.

Method protects air-sensitive 2D materials from oxidation.

Enables fabrication of atomic printed circuit boards.

Abstract

Atomically thin 2D materials span the common components of electronic circuits as metals, semi-conductors, and insulators, and can manifest correlated phases such as superconductivity, charge density waves, and magnetism. An ongoing challenge in the field is to incorporate these 2D materials into multi-layer hetero-structures with robust electrical contacts while preventing disorder and degradation. In particular, preserving and studying air-sensitive 2D materials has presented a significant challenge since they readily oxidize under atmospheric conditions. We report a new technique for contacting 2D materials, in which metal via contacts are integrated into flakes of insulating hexagonal boron nitride, and then placed onto the desired conducting 2D layer, avoiding direct lithographic patterning onto the 2D conductor. The metal contacts are planar with the bottom surface of the boron nitride and form robust contacts to multiple 2D materials. These structures protect air-sensitive 2D materials for months with no degradation in performance. This via contact technique will provide the capability to produce atomic printed circuit boards that can form the basis of more complex multi-layer heterostructures.