Centimeter-Scale 2D van der Waals Vertical Heterostructures Integrated on Deformable Substrates Enabled by Gold Sacrificial Layer-Assisted Growth.
basic_science · Level V
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- Record sourced from PubMed, PMID 28945439.
- Also identified by DOI 10.1021/acs.nanolett.7b02776.
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Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as molybdenum or tungsten disulfides (MoS<sub>2</sub> or WS<sub>2</sub>) exhibit extremely large in-plane strain limits and unusual optical/electrical properties, offering unprecedented opportunities for flexible electronics/optoelectronics in new form factors. In order for them to be technologically viable building-blocks for such emerging technologies, it is critically demanded to grow/integrate them onto flexible or arbitrary-shaped substrates on a large wafer-scale compatible with the prevailing microelectronics processes. However, conventional approaches to assemble them on such unconventional substrates via mechanical exfoliations or coevaporation chemical growths have been limited to small-area transfers of 2D TMD layers with uncontrolled spatial homogeneity. Moreover, additional processes involving a prolonged exposure to strong chemical etchants have been required for the separation of as-grown 2D layers, which is detrimental to their material properties. Herein, we report a viable strategy to universally combine the centimeter-scale growth of various 2D TMD layers and their direct assemblies on mechanically deformable substrates. By exploring the water-assisted debonding of gold (Au) interfaced with silicon dioxide (SiO<sub>2</sub>), we demonstrate the direct growth, transfer, and integration of 2D TMD layers and heterostructures such as 2D MoS<sub>2</sub> and 2D MoS<sub>2</sub>/WS<sub>2</sub> vertical stacks on centimeter-scale plastic and metal foil substrates. We identify the dual function of the Au layer as a growth substrate as well as a sacrificial layer which facilitates 2D layer transfer. Furthermore, we demonstrate the versatility of this integration approach by fabricating centimeter-scale 2D MoS<sub>2</sub>/single walled carbon nanotube (SWNT) vertical heterojunctions which exhibit current rectification and photoresponse. This study opens a pathway to explore large-scale 2D TMD van der Waals layers as device building blocks for emerging mechanically deformable electronics/optoelectronics.