Spectroscopic Evaluation of Charge-transfer Doping and Strain in Graphene/MoS2 Heterostructures

Abstract

It is important to study the van der Waals interface in emerging vertical heterostructures based on layered two-dimensional (2D) materials. Being atomically thin, 2D materials are susceptible to significant strains as well as charge transfer doping across the interfaces. Here we use Raman and photoluminescence (PL) spectroscopy to study the interface between monolayer graphene/MoS2 heterostructures prepared by mechanical exfoliation and layer-by-layer transfer. By using correlation analysis between the Raman modes of graphene and MoS2 we show that both layers are subjected to compressive strain and charge transfer doping following mechanical exfoliation and thermal annealing. Furthermore, we show that both strain and carrier concentration can be modulated in the heterostructures with additional thermal annealing. Our study highlights the importance of considering both mechanical and electronic coupling when characterizing the interface in van der Waals heterostructures, and demonstrates a method to tune their electromechanical properties.

5 Figures, 1 table

References in corpus (12)

• Electric Field Effect in Atomically Thin Carbon Films
• Electrochemically Top Gated Graphene: Monitoring Dopants by Raman Scattering
• Uniaxial Strain in Graphene by Raman Spectroscopy: G peak splitting, Gruneisen Parameters and Sample Orientation
• Vertical Field Effect Transistor based on Graphene-WS2 Heterostructures for flexible and transparent electronics
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Optical Separation of Mechanical Strain from Charge Doping in Graphene
• Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy
• Raman Fingerprint of Charged Impurities in Graphene
• Probing the Intrinsic Properties of Exfoliated Graphene: Raman Spectroscopy of Free-Standing Monolayers
• Fast pick up technique for high quality heterostructures of bilayer graphene and hexagonal boron nitride
• Graphene under hydrostatic pressure
• Enhanced Raman and photoluminescence response in monolayer MoS${}_2$ due to laser healing of defects