An ultrasensitive molybdenum-based double-heterojunction phototransistor

Area of Science:

• Materials Science
• Nanotechnology
• Device Physics

Background:

• Two-dimensional (2D) materials offer unique optoelectronic properties for photodetectors.
• Atomic thickness of 2D materials limits intrinsic detection ability.
• Photogating enhances responsivity but increases noise, limiting detectivity.

Purpose of the Study:

• To develop a high-performance photodetector using 2D materials.
• To overcome the limitations of low responsivity and high noise in 2D photodetectors.
• To explore a novel photo-induced barrier-lowering (PIBL) mechanism.

Main Methods:

• Fabrication of a molybdenum-based phototransistor with a MoS2 channel.
• Utilized α-MoO3-x as contact electrodes.
• Investigated the photo-induced barrier-lowering (PIBL) mechanism in a double heterojunction device.

Main Results:

• Achieved an ultrahigh detectivity of 9.8 × 10^16 cm Hz^1/2 W^-1.
• Demonstrated positive feedback through double heterojunctions.
• The PIBL mechanism significantly enhanced photosensitivity.

Conclusions:

• The developed MoS2 phototransistor with α-MoO3-x contacts exhibits exceptional performance.
• The double heterojunction PIBL mechanism is effective for ultrahigh photosensitivity.
• This work provides a new technique for fabricating advanced 2D material-based phototransistors.