Metal/MoS2 Heterostructure for Photonic Applications

2-dimensional (2D) materials, due to their unique electronic and optical properties, are becoming increasingly attractive for applications in nanotechnology, electronics, photonics and quantum applications. However, considering existing challenges in the fabrication of large-scale heterostructures, the potential of 2D material in photonic devices are still not completely explored and understood. Here, propose to grow metal/MoS2 heterostructures which can be used for as optical absorbers, metamaterials for biosensing applications and for other photonic applications. It has been reported that Ag grows in a Volmer-Weber mode and the deposition can cause damage to ML MoS₂ [1]. To overcome this challenge, we will grow the metal (silver, Ag) and 2D material, MoS₂, using pulsed laser deposition (PLD) to achieve monolayer control and conformal growth.<br/>Ag is an excellent plasmonic material, and is able to evanescently confine electromagnetic waves and support local surface plasma resonance, enhancing the intensity of the electromagnetic waves near the interface. Monolayer (ML) MoS₂, acting as a 2D direct bandgap semiconductor, can generate electron-hole pairs and release photons during the light-matter interaction. Different from traditional metal-dielectric plasmonic devices, a Schottky barrier exist at the Ag/ML MoS₂ interface, and this quantum confinement effect can lead to selective wavelength absorption and emission due to modified density of states. These characteristics make the Ag/monolayer MoS2/Ag structure particularly attractive for advanced optoelectronic applications, leveraging the unique properties of MoS2 to enhance the functionality beyond what is possible with traditional plasmonic devices.<br/>In this work, PLD was used for the growth of the heterostructures of Ag/ML MoS₂/Ag deposition. PLD demonstrated an extraordinary performance of growing large-area and high-quality monolayer MoS₂ as well as silver thin films. The current RMS roughness we achieved for ML MoS₂ and 75nm silver thin film are 0.2nm and 1.7nm respectively. Also, the growth procedure ensured that we were able to grow the heterostructure under high vacuum (~10^-7 Torr) or oxygen isolated condition, preventing the formation of oxide at the interface between silver and MoS₂. Simulation results for these heterostructures using density functional theory (DFT) and experimental characterization results of these heterostructures will be presented.<br/><br/>References:<br/>[1] K. Schauble et al., “Uncovering the Effects of Metal Contacts on Monolayer MoS2,” ACS nano, vol. 14, no. 11, pp. 14798–14808, Sep. 2020, doi: https://doi.org/10.1021/acsnano.0c03515.