Two-dimensional GaN/Si heterojunctions towards high-performance UV-B photodetectors

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Two-dimensional (2D) Gallium Nitride (GaN) offers desirable properties like tunable bandgap, high electron mobility, and stability, making it suitable for UV-B photodetectors (PDs).
• Challenges remain in achieving large-scale synthesis and bandgap engineering for 2D GaN-based UV-B PDs.

Purpose of the Study:

• To propose and demonstrate novel UV-B PDs based on wafer-scale 2D GaN/Si heterojunctions.
• To achieve simultaneous large-scale preparation and band engineering of 2D GaN for enhanced photodetector performance.

Main Methods:

• Wafer-scale synthesis of 2D GaN was performed using a two-step method involving magnetron sputtering and high-temperature ammonolysis.
• The bandgap of 2D GaN was precisely regulated to 3.6 eV and 4.1 eV by controlling its thickness.

Main Results:

• Novel UV-B PDs based on 2D GaN/Si heterojunctions were successfully fabricated.
• The fabricated PDs exhibited a photoresponsivity of 2.2 A/W at 308 nm under 1 V bias.
• The devices demonstrated fast response speeds with rise and decay times of 1.3 ms and 1.1 ms, respectively.

Conclusions:

• This work presents a viable solution for high-performance UV-B PDs through controllable growth of 2D GaN.
• The developed synthesis strategy significantly expands the application potential of 2D GaN in UV optoelectronics.