Ultrahigh Photo-Responsivity and Detectivity in  2D Bismuth Sulfide Photodetector for Vis-NIR Radiation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Bismuth sulfide (Bi2S3) is a 2D material with a direct energy bandgap and broad optical absorption.
• 2D materials are increasingly explored for advanced electronic and optoelectronic devices.

Purpose of the Study:

• To investigate the temperature-dependent transport characteristics of 2D Bi2S3 in a field-effect transistor (FET) photodetector.
• To explore the potential of 2D Bi2S3 as a high-performance photodetector material.

Main Methods:

• Fabrication of a 2D Bi2S3 FET photodetector.
• Temperature-dependent electrical resistance measurements.
• Photoluminescence, time-resolved photoluminescence, Hall measurements, and energy dispersive X-ray spectroscopy.
• Density functional theory (DFT) calculations for defect analysis.

Main Results:

• Observed a 99.26% reduction in electrical resistance at 10 K compared to 300 K, attributed to defects like bismuth and sulfur vacancies.
• Achieved ultrahigh responsivity (≈10^6 A/W) and detectivity (≈10^14 Jones).
• Measured external quantum efficiency of ≈10^7% across a broad spectrum (532-1064 nm) with low noise-equivalent power.

Conclusions:

• 2D Bi2S3 exhibits anomalous temperature-dependent transport properties crucial for photodetector performance.
• Defects significantly influence the material's characteristics, enabling exceptional optoelectronic behavior.
• The Bi2S3 FET photodetector demonstrates superior performance, surpassing other 2D photodetectors.