Schottky Diode Leakage Current Fluctuations: Electrostatically Induced Flexoelectricity in Silicon

Area of Science:

• Nanotechnology
• Materials Science
• Electrical Engineering

Background:

• Atomic force microscopy (AFM) is crucial for nanoscale electrical characterization in semiconductor and nanotechnology industries.
• Reproducibility challenges in electrical AFM measurements stem from surface contamination, heating, and tip instability.
• Nanoscale Schottky diodes on silicon offer a model system for studying electrical properties.

Purpose of the Study:

• To investigate the impact of voltage-dependent adhesion forces on AFM tip behavior.
• To elucidate the mechanism by which tip rotation affects silicon-based nanoscale devices.
• To understand the implications for device design and emerging energy harvesting applications.

Main Methods:

• Assembled nanoscale Schottky diodes on oxide-free silicon crystals with controlled surface chemistry.
• Utilized atomic force microscopy (AFM) to probe electrical properties and tip-surface interactions.
• Analyzed voltage-dependent adhesion forces and their effect on tip rotation and induced strain gradients.

Main Results:

• Voltage-dependent adhesion forces induce significant rotation of the AFM platinum tip.
• Tip rotation generates a strain gradient on the silicon surface, creating a flexoelectric reverse bias.
• This flexoelectric bias increases diode leakage and shifts the knee voltage in silicon Schottky diodes.

Conclusions:

• Flexoelectric effects arising from AFM tip rotation can significantly alter the electrical characteristics of nanoscale silicon devices.
• Findings provide critical insights for designing and characterizing silicon-based devices, particularly those under strain.
• The study has implications for advanced energy harvesting technologies like triboelectric nanogenerators (TENGs).