Ultrafast Self-Driven WSe₂ Photodetectors with Bottom Schottky Contacts

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Conventional two-dimensional (2D) Schottky photodetectors face challenges like light shadowing and contact damage.
• These issues lead to Fermi-level pinning and reduced device performance.

Purpose of the Study:

• To design and fabricate a high-performance bottom-electrode Schottky photodetector (BE-Schottky PD) using a Cr/WSe2/Au heterostructure.
• To overcome the limitations of conventional top-contact designs, improving light absorption and mitigating Fermi-level pinning.

Main Methods:

• Fabrication of a BE-Schottky PD with the bottom Schottky Cr electrode integrated into pre-etched SiO2 substrate trenches.
• Formation of a high-quality van der Waals Cr/WSe2 interface.
• Characterization of the photodetector's electrical and photoresponse properties.

Main Results:

• The unique bottom-electrode design eliminates optical shadowing, maximizing light absorption.
• The device achieved an excellent rectification ratio of 1.07 × 10^4 and an ideality factor of 1.11.
• Demonstrated rapid photoresponse with a fall time of 3.8 µs under 532 nm laser illumination at zero bias, indicating self-powered operation.

Conclusions:

• The developed BE-Schottky PD offers a high-performance solution for optoelectronic applications.
• The study highlights the potential of 2D materials in creating efficient, low-power, and ultrasensitive photodetectors using simple, industry-compatible processes.