High-Responsivity Multilayer MoSe₂ Phototransistors with Fast Response Time.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Devices

Background:

• Transition metal dichalcogenides (TMDs) exhibit promising optoelectronic properties for phototransistors.
• Molybdenum diselenide (MoSe2) offers higher optical absorbance compared to MoS2 but receives less research focus.
• Existing MoSe2 phototransistors have not reached their full performance potential.

Purpose of the Study:

• To investigate the performance of multilayer MoSe2 phototransistors.
• To demonstrate high responsivity, detectivity, and fast response times in MoSe2 devices.
• To propose a model explaining the operational mechanism of MoSe2 phototransistors.

Main Methods:

• Fabrication of multilayer MoSe2 phototransistors using a bottom-gate thin-film transistor configuration.
• Characterization of device performance under 650-nm laser illumination.
• Development of a qualitative model based on photoconductive and photogating effects.

Main Results:

• Achieved record-breaking responsivity (1.4 × 10^5 AW^-1) and specific detectivity (5.5 × 10^13 jones) for MoSe2 phototransistors.
• Demonstrated a fast response time of 1.7 ms, the fastest reported for MoSe2 phototransistors.
• Presented a qualitative model elucidating device operation through combined photoconductive and photogating mechanisms.

Conclusions:

• Multilayer MoSe2 phototransistors can achieve state-of-the-art performance.
• MoSe2 is a highly promising material for next-generation photodetectors.
• Further performance enhancements are achievable through optimized device engineering.