Layer-Dependent Electron Transfer and Recombination Processes in MoS₂/WSe₂ Multilayer Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Optimizing charge transfer in 2D materials is crucial for advanced semiconductor devices.
• Transition metal disulfide (TMD) heterostructures with type II band alignment exhibit robust charge transfer.
• Dielectric layers like hexagonal boron nitride (hBN) can modulate charge transfer by isolating monolayers.

Purpose of the Study:

• To investigate an alternative method for tuning electron transfer and recombination rates in 2D heterostructures.
• To explore the layer-dependent and asymmetric effects on charge transfer in molybdenum disulfide (MoS₂)/tungsten diselenide (WSe₂) multilayer heterostructures.
• To compare the effectiveness of layer number manipulation with dielectric intercalation for controlling charge transfer.

Main Methods:

• Fabrication of n-layer MoS₂/m-layer WSe₂ (nLMoS₂/mLWSe₂) multilayer heterostructures.
• Experimental investigation of electron transfer and charge recombination rates.
• Comparative analysis of heterostructures with varying layer numbers and the inclusion of hBN.

Main Results:

• Electron transfer rate is strongly dependent on the number of layers in nLMoS₂/mLWSe₂ heterostructures.
• Asymmetry in electron transfer rates was observed based on the layer count of donor and acceptor monolayers.
• The 1LMoS₂/2LWSe₂ heterostructure demonstrated significantly slower electron transfer (∼2.3 times) and charge recombination (∼12 times) compared to 1LMoS₂/1LWSe₂.
• These rates were found to be competitive with those in heterostructures incorporating an hBN dielectric layer.

Conclusions:

• The number of layers in 2D heterostructures provides a viable route to control charge transfer and recombination dynamics.
• Layer-dependent effects offer an alternative strategy to dielectric intercalation for device optimization.
• Non-interfacial electron transfer across multiple layers is hindered by built-in electric fields, impacting device performance.