Gate-Tunable Electron Trap Dynamics in Defect-Engineered MoS₂-WSe₂ Heterostructures for Broadband Photodetection.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Defect-induced trap states in MoS2-WSe2 heterostructures enable sub-bandgap photon absorption.
• Understanding electron trap dynamics is crucial for optimizing photodetector performance.

Purpose of the Study:

• To quantitatively investigate gate-controlled electron trap dynamics.
• To elucidate the influence of these dynamics on spectral and temporal characteristics of MoS2-WSe2 heterostructure photodetectors.

Main Methods:

• Utilized a MoS2-WSe2 heterostructure photodetector.
• Applied varying gate voltages to modulate electron trap occupation.
• Measured spectral responsivity and photocurrent rise/fall times.

Main Results:

• Extended photodetection range up to 1650 nm due to trap states.
• Gate voltage shifts Fermi level, altering electron trap occupation and absorption.
• Shortened photocurrent rising time from 480 ms to 1.3 ms with increased gate voltage.
• Prolonged falling time due to reduced trap-assisted recombination.

Conclusions:

• Gate bias dynamically modulates spectral responsivity and photoresponse time.
• The device functions as a tunable photodetector for specific applications.
• Provides fundamental insights into trap-assisted photodetection mechanisms and gate-controlled optoelectronics.