Highly Sensitive Photodetectors Based on Monolayer MoS₂ Field-Effect Transistors

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Molybdenum disulfide (MoS₂) exhibits excellent optoelectronic properties for photodetector development.
• Existing MoS₂ phototransistors often use back-gate FETs requiring high voltages (up to 70 V), limiting array integration.
• High operating voltages hinder the modulation of individual devices in photodetector arrays.

Purpose of the Study:

• To fabricate and investigate the electric and photoelectric properties of buried-gate FETs based on CVD-grown monolayer MoS₂.
• To demonstrate a low-voltage, high-performance photodetector solution.
• To overcome the limitations of traditional back-gate MoS₂ phototransistors.

Main Methods:

• Fabrication of buried-gate field-effect transistors (FETs) using chemical vapor deposition (CVD)-grown monolayer MoS₂.
• Systematic investigation of electrical and photoelectric characteristics.
• Measurement of photoresponsivity and response speed under varying gate bias conditions.

Main Results:

• Achieved a photoresponsivity of approximately 6.86 A/W at 395 nm with zero gate bias and 2.57 mW/cm² light intensity.
• Demonstrated a nearly tenfold increase in photoresponsivity with an 8 V buried-gate voltage.
• Measured a response speed of approximately 350 ms for the buried-gate MoS₂ FET phototransistors.

Conclusions:

• Buried-gate MoS₂ FETs offer a promising low-voltage alternative for high-performance photodetectors.
• The developed devices show potential for practical applications in photodetector arrays.
• These findings advance the integration of MoS₂-based optoelectronics.