Large Area Automated Characterisation of Chemical Vapour Deposition Grown Monolayer Transition Metal Dichalcogenides Through Photoluminescence Imaging
arXiv:1911.03633 · doi:10.1038/s41699-020-0146-y
Abstract
CVD growth is capable of producing multiple single crystal islands of atomically thin TMDs over large area substrates, with potential control of their morphology, lateral size, and epitaxial alignment to substrates with hexagonal symmetry. Subsequent merging of epitaxial domains can lead to single-crystal monolayer sheets - a step towards scalable production of high quality TMDs. For CVD growth to be effectively used for such production it is necessary to be able to rapidly assess the quality of material across entire large area substrates. To date characterisation has been limited to sub 0.1 mm2 areas, where the properties measured are not necessarily representative of an entire sample. Here, we apply photoluminescence (PL) imaging and computer vision techniques to create an automated analysis for large area samples of semiconducting TMDs, measuring the properties of island size, density of islands, relative PL intensity and homogeneity, and orientation of triangular domains. The analysis is applied to 20x magnification optical microscopy images that completely map samples of WSe2 on hBN, 5.0 mm x 5.0 mm in size, and MoSe2-WS2 on SiO2/Si, 11.2 mm x 5.8 mm in size. For the latter sample 100,245 objects were identified and their properties measured, with an orientation extracted from 27,779 objects that displayed a triangular morphology. In the substrates studied, two prevailing orientations of epitaxial growth were observed in WSe2 grown on hBN and four predominant orientations were observed in MoSe2, initially grown on c-plane sapphire. The proposed analysis will greatly reduce the time needed to study freshly synthesised material over large area substrates and provide feedback to optimise growth conditions, advancing techniques to produce high quality TMD monolayer sheets for commercial applications.
arXiv comment32 pages including Supplementary Information, 6 figures
References in corpus (20)
- Atomically thin MoS2: A new direct-gap semiconductor
- Two Dimensional Atomic Crystals
- Van der Waals heterostructures
- Electrically Tunable Excitonic Light Emitting Diodes based on Monolayer WSe2 p-n Junctions
- Light-emitting diodes by bandstructure engineering in van der Waals heterostructures
- Solar-energy conversion and light emission in an atomic monolayer p-n diode
- Moiré Excitons in Van der Waals Heterostructures
- Signatures of moiré-trapped valley excitons in MoSe/WSe heterobilayers
- Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
- Resonantly hybridised excitons in moiré superlattices in van der Waals heterostructures
- Evolution of Interlayer Coupling in Twisted MoS2 Bilayers
- Laser-thinning of MoS2: on demand generation of a single-layer semiconductor
- Atomically thin quantum light emitting diodes
- Momentum-space indirect interlayer excitons in transition metal dichalcogenide van der Waals heterostructures
- Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures
- Direct growth of single- and few-layer MoS2 on h-BN with preferred relative rotation angles
- An innovative way of etching MoS2: Characterization and mechanistic investigation
- Imaging of interlayer coupling in van der Waals heterostructures using a bright-field optical microscope
- Topography preserved microwave plasma etching for top-down layer engineering in MoS2 and other van der Waals materials
- The Atomic and Electronic structure of 0° and 60° grain boundaries in MoS2