Scalable transparent conductive thin films with electronically passive interfaces for direct chemical vapor deposition of 2D materials

TL;DR

This paper introduces a scalable, transparent support structure with passive interfaces for direct CVD growth of 2D materials, enabling improved optical and electronic properties for device applications.

Contribution

The authors develop a novel nc-C/AlOx support that allows direct CVD growth of 2D materials with enhanced optical contrast and charge transport, advancing scalable 2D material fabrication.

Findings

Strong optical contrast for monolayer flakes on the support

Ten-fold photoluminescence enhancement of MoS2 flakes

Interfacial charge injection demonstrated via tunneling across AlOx

Abstract

We present a novel transparent conductive support structure for two-dimensional (2D) materials that provides an electronically passive 2D/3D interface while also enabling facile interfacial charge transport. This structure, which comprises an evaporated nanocrystalline carbon (nc-C) film beneath an atomic layer deposited alumina (ALD AlOx) layer, is thermally stable and allows direct chemical vapor deposition (CVD) of 2D materials onto the surface. When the nc-C/AlOx is deposited onto a 270 nm SiO2 layer on Si, strong optical contrast for monolayer flakes is retained. Raman spectroscopy reveals good crystal quality for MoS2 and we observe a ten-fold photoluminescence intensity enhancement compared to flakes on conventional Si/SiO2. Tunneling across the ultrathin AlOx enables interfacial charge injection, which we demonstrate by artifact-free scanning electron microscopy and photoemission electron microscopy. Thus, this combination of scalable fabrication and electronic conductivity across a weakly interacting 2D/3D interface opens up new application and characterization opportunities for 2D materials.