Reversible Diode Effect in Truncated-pyramid-shaped Bi₂O₂Se Modulated by Tip-Force-Induced Flexoelectric Field.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Tunable diode devices are crucial for next-generation electronics like artificial synapses.
• Achieving high-performance, dynamically controllable diodes remains a key research challenge.

Purpose of the Study:

• To investigate tunable diode behavior in Bi2O2Se microstructures.
• To explore the modulation of electrical properties by internal and external electric fields.

Main Methods:

• Fabrication of truncated-pyramid Bi2O2Se microstructures on HOPG substrates.
• Construction of a W-metal-probe-BOS-HOPG system for electrical characterization.
• Systematic investigation of diode behavior under varying inclination angles and tip forces.
• Finite element simulations to analyze electric field distribution.

Main Results:

• Decreasing inclination angle of Bi2O2Se microstructures enhanced the diode effect, reaching a rectification ratio of 10.
• Tip-force-induced flexoelectric fields (E_tip-flexo) competed with the built-in electric field (E_built-in).
• Reversible diode behavior and continuous tuning of rectification ratio (down to <0.1) were achieved by modulating the total electric field.

Conclusions:

• The interplay between E_built-in and E_tip-flexo enables dynamic control over diode characteristics.
• This work offers fundamental insights into microscale flexoelectric effects for tunable electronic device design.
• The findings provide a theoretical basis for developing advanced programmable logic circuits and artificial synapses.