Defect-mediated carrier trapping and nonradiative recombination in two-dimensional sliding ferroelectrics

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) ferroelectrics are promising for next-generation electronics like non-volatile memories and optoelectronic neuromorphic devices.
• The influence of defects on photoinduced carrier dynamics in these materials is not well understood.

Purpose of the Study:

• To investigate the role of sulfur (S) vacancies in rhombohedral-stacked MoS2 bilayers.
• To understand how these vacancies affect carrier trapping and nonradiative recombination.

Main Methods:

• Systematic investigation of S vacancies in MoS2 bilayers.
• Analysis of photoinduced carrier dynamics, including trapping and recombination processes.

Main Results:

• S vacancies introduce localized electron trap states within the MoS2 bandgap.
• These trap states facilitate a highly efficient two-step nonradiative recombination pathway.
• This pathway, involving low-frequency phonon modes, accelerates recombination and reduces carrier lifetime.

Conclusions:

• Defects, specifically S vacancies, significantly impact carrier dynamics in 2D ferroelectrics.
• Understanding and engineering these defects are crucial for controlling carrier behavior.
• The findings provide insights for designing improved 2D ferroelectric-based optoelectronic devices.