Highly Sensitive, Encapsulated MoS2 Photodetector with Gate Controllable Gain and Speed

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Two-dimensional molybdenum disulfide (MoS2) shows promise for sensitive photodetection due to its thin profile and bandgap.
• Environmental adsorbates negatively impact MoS2 photodetector performance due to their high surface-to-volume ratio.

Purpose of the Study:

• To create stable, high-performance monolayer and bilayer MoS2 photodetectors.
• To investigate the effects of atomic layer deposited hafnium oxide encapsulation on MoS2 device properties.

Main Methods:

• Encapsulation of monolayer and bilayer MoS2 with atomic layer deposited hafnium oxide.
• Characterization of electronic properties, responsivity, and temporal response under varying gate voltages.

Main Results:

• Encapsulated MoS2 photodetectors exhibited enhanced stability and electronic properties, including n-type doping, reduced hysteresis, and lower resistance.
• Device responsivity (R) and temporal response (t) were tunable over several orders of magnitude (R ~ 10-10(4) A/W, t ~ 10 ms to 10 s).
• Record sensitivity (D* ≥ 7.7 × 10(11) Jones) was achieved at strong negative gate voltage with high-speed operation.

Conclusions:

• Atomic layer deposited hafnium oxide encapsulation effectively protects MoS2 from environmental degradation, leading to stable, high-performance photodetectors.
• Tunable optoelectronic properties and record sensitivity demonstrate the potential of encapsulated MoS2 for advanced applications.
• This work highlights the importance of encapsulation for transition metal dichalcogenide optoelectronics and enables future flexible device development.