Novel Colloidal MoS2 Quantum Dot Heterojunctions on Silicon Platforms for Multifunctional Optoelectronic Devices

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Molybdenum disulfide (MoS2) is a promising 2D material for electronic and optoelectronic applications.
• Developing silicon-compatible fabrication methods for MoS2-based devices is crucial for integration into existing technologies.
• Colloidal quantum dots offer tunable optical and electronic properties and scalable synthesis.

Purpose of the Study:

• To demonstrate silicon-compatible wafer-scale MoS2 heterojunctions using colloidal quantum dots for the first time.
• To investigate the optical and photodetection properties of these 0D/3D heterojunctions.
• To evaluate the stability and performance metrics of the fabricated devices.

Main Methods:

• Fabrication of n-MoS2/p-Si 0D/3D heterojunctions using colloidal quantum dots.
• Characterization of MoS2 quantum dots' size-dependent emission properties at room temperature.
• Time-correlated single-photon counting spectroscopy to study charge carrier dynamics.
• Electrical and optical measurements to assess rectification, electroluminescence, and photodetection capabilities.

Main Results:

• Achieved silicon-compatible wafer-scale MoS2 heterojunctions for the first time.
• Observed size-dependent direct band gap emission of MoS2 quantum dots with stable white light electroluminescence (450-800 nm) from 10-350 K.
• Demonstrated excellent rectification behavior and high photodetection performance with peak responsivity (~0.85 A/W) and detectivity (~8 × 10^11 Jones) for 2 nm MoS2 QDs.

Conclusions:

• Colloidal quantum dot-based MoS2 heterojunctions are a viable route for silicon-compatible wafer-scale optoelectronic devices.
• The fabricated devices exhibit promising performance for both light emission and photodetection applications.
• The achieved performance metrics exceed those of previously reported large-area photodetectors based on 2D materials.