Multilayer 2D germanium phosphide (GeP) infrared phototransistor

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Layered two-dimensional (2D) materials are key for advanced optoelectronics.
• Graphene, black phosphorus, and black arsenic phosphorus are well-studied 2D semiconductors.
• Novel group IV-V 2D semiconductors like GeAs and SiAs remain underexplored for broadband applications.

Purpose of the Study:

• To investigate the potential of 2D Germanium Phosphide (GeP) for optoelectronics.
• To develop and characterize a high-performance, gate-tunable photodetector based on multilayered 2D GeP.
• To explore the broadband photodetection capabilities of 2D GeP, particularly in the short-wavelength infrared (SWIR) regime.

Main Methods:

• Fabrication of a multilayered 2D GeP photodetector with a back-gate geometry.
• Characterization of the device's electrical properties, including p-type behavior at room temperature.
• Measurement of spectral response, responsivity, detectivity, and dark current under varying illumination and bias conditions.

Main Results:

• A gate-tunable 2D GeP photodetector exhibiting p-type behavior at room temperature was successfully developed.
• Broadband spectral response was observed, spanning from ultraviolet to optical communication wavelengths.
• Peak responsivity of 25.5 A/W at 1310 nm and high detectivity (∼1×10¹¹ cm.Hz^1/2.W^-1) were achieved under nanowatt illumination.
• Low dark current (40-250 nA) and excellent device stability and reproducibility were demonstrated.

Conclusions:

• 2D GeP is a promising material for high-performance photodetectors.
• The developed GeP photodetector offers broad optical tunability, making it suitable for optical communication and low-light-level detection.
• This work highlights 2D GeP as a viable alternative material for mid-infrared applications.