Van der Waals injection-molded crystals

TL;DR

This paper introduces a novel method to grow complex, low-disorder, van der Waals crystal nanostructures with precise geometries by injecting molten materials within molds, encapsulating them for protection and control.

Contribution

The authors develop a new technique for shaping van der Waals crystals into arbitrary geometries during growth, reducing disorder compared to traditional nanofabrication methods.

Findings

Produced ultraflat, thin crystals with complex geometries

Achieved large single-crystals covering entire mold shapes

Demonstrated reduced disorder scattering in transport measurements

Abstract

Shaping low-dimensional crystals into precise geometries with low disorder is an outstanding challenge. Here, we present a method to grow single crystals of arbitrary geometry within van der Waals (vdW) materials. By injecting molten material between atomically-flat vdW layers within an SiO2 mold, we produce ultraflat and thin crystals of bismuth, tin, and indium that are shaped as hallbars, rings, and nanowires. The crystals are grown fully encapsulated in hexagonal boron nitride, a vdW material, providing protection from oxidation. Varying the depth of the mold allows us to control the crystal thickness from ten to a hundred nanometers. Structural measurements demonstrate large single-crystals encompassing the entire mold geometry, while transport measurements show reduced disorder scattering. This approach offers a means to produce complex single-crystal nanostructures without the disorder introduced by post-growth nanofabrication.