High Responsivity Vacuum Nano-Photodiode Using Single-Crystal CsPbBr₃ Micro-Sheet

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Vacuum photodiodes offer ultrafast electromagnetic radiation conversion via ballistic electron transport.
• Low photoelectric conversion efficiency remains a key limitation for vacuum photodiode adoption.

Purpose of the Study:

• To develop an on-chip integrated vacuum nano-photodiode with enhanced photoelectric conversion efficiency.
• To investigate the performance of a CsPbBr3 cathode in a nano-photodiode structure.

Main Methods:

• Fabrication of an on-chip vacuum nano-photodiode using a Si-tip anode and a single-crystal CsPbBr3 cathode with ~30 nm separation.
• Characterization of the photodiode's performance under 532-nm laser illumination.
• Electrostatic field simulation to analyze the cathode's depletion and electric field effects.

Main Results:

• The vacuum nano-photodiode operated at a low driving voltage (15 V) with ultra-low dark current (50 pA).
• Achieved high photoresponsivity (1.75 AW⁻¹@15 V) and an external quantum efficiency up to 400%.
• Simulations revealed a built-in electric field enhancing electron-hole pair dissociation and a photoconductive effect narrowing the vacuum barrier.

Conclusions:

• The integrated perovskite vacuum nano-photodiode demonstrates significantly enhanced photoelectric conversion efficiency.
• The device shows potential for highly sensitive, perovskite-based vacuum optoelectronic applications.
• The design leverages nanoscale vacuum channels and material properties for improved performance.