Individual Single-Crystalline Irregular In₂O₃ Microcavity for Ultrasensitive Semiconductor-Based SERS Biosensor

Area of Science:

• Materials Science
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity and water-interference-free detection.
• Developing single-particle semiconductor SERS substrates without gap-enhancement is a key challenge.

Purpose of the Study:

• To create an ultrasensitive semiconductor SERS system using a novel microcavity structure.
• To investigate the role of morphology and interfacial charge transfer in enhancing SERS performance.

Main Methods:

• Fabrication of highly crystalline irregular hexagonal prism Indium Oxide (I-In2O3) microcavities.
• Finite-difference time-domain simulations and photoluminescence spectroscopy to confirm microcavity formation.
• Aberration-corrected electron microscopy and density functional theory calculations to analyze material structure and electronic properties.

Main Results:

• Confirmed whispering-gallery-mode microcavity formation on the I-In2O3 platform, enhancing light confinement.
• Observed contracted lattice parameters and electronic band restructuring in I-In2O3 due to compressive lattice strain.
• Demonstrated quantitative and multiplexing capabilities for rapid antibiotic detection using the I-In2O3 SERS system.

Conclusions:

• The I-In2O3 microcavity platform enables ultrasensitive, single-particle SERS detection.
• Morphology-induced light accumulation and strain-improved charge transfer are crucial for enhanced SERS.
• This work provides a new approach for developing supersensitive semiconductor SERS sensors.