Ultrahigh photoresponsivity MoS₂ photodetector with tunable photocurrent generation mechanism.

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Two-dimensional (2D) material photodetectors on SiO2/Si substrates are widely studied.
• Existing devices face limitations like high gate voltage and low photoresponsivity due to poor light absorption in 2D materials.

Purpose of the Study:

• To develop a high-performance photodetector using 2D materials.
• To overcome the limitations of low light absorption and high gate voltage in conventional 2D material photodetectors.

Main Methods:

• Fabrication of a Molybdenum disulfide (MoS2) photodetector on an Al2O3/Indium Tin Oxide (ITO)/SiO2/Si substrate.
• Utilizing the reflective interface of the stacked substrate to enhance light absorption by the MoS2 layer.
• Employing a thin, high-κ Al2O3 dielectric layer for improved gate control.

Main Results:

• Achieved ultrahigh photoresponsivity of 2.7 × 10^4 A/W.
• Demonstrated a current ON/OFF ratio exceeding 10^9 with a gate voltage below 2 V.
• Observed enhanced gate regulation, resulting in a mobility of 84 cm²/V·s and a subthreshold swing of 104 mV/dec.
• Identified two distinct photocurrent generation mechanisms tunable by gate voltage.

Conclusions:

• The reflection-enhancement substrate significantly improves light absorption and photodetector performance.
• The developed MoS2 photodetector exhibits superior photoresponsivity, ON/OFF ratio, and gate control.
• This approach offers a promising strategy for advancing 2D material-based photodetector technology.