Ubiquitous Antiparallel Domains in 2D Hexagonal Boron Nitride Uncovered by Interferometric Nonlinear Optical Imaging

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Hexagonal boron nitride (hBN) is crucial for 2D technologies but assessing its large-area crystalline quality is challenging.
• Antiparallel domains and structural defects in hBN have historically evaded optical detection methods.
• Current methods struggle with non-destructive, large-area characterization of hBN crystalline integrity.

Purpose of the Study:

• To develop a non-destructive optical method for assessing large-area crystalline quality in 2D hexagonal boron nitride (hBN).
• To investigate the formation and impact of antiparallel domains and structural defects in hBN.
• To establish a unified framework for evaluating crystalline quality across various hBN growth methods.

Main Methods:

• Utilized interferometric second-harmonic generation (SHG) imaging to probe lattice orientation and structural integrity.
• Applied SHG intensity as a direct optical metric for quantifying domain disorder.
• Correlated SHG findings with Raman spectroscopy to establish a comprehensive quality evaluation framework.

Main Results:

• Demonstrated that SHG imaging can effectively detect antiparallel domains and structural defects in 2D hBN.
• Quantified the impact of antiparallel domains on the overall crystalline order.
• Showcased SHG intensity as a sensitive indicator of domain disorder across films from ten different growth routes.
• Established a unified framework for crystalline quality assessment by correlating SHG with Raman spectroscopy.

Conclusions:

• Interferometric SHG imaging is a powerful, non-destructive tool for wide-area structural characterization of 2D hBN.
• The developed SHG method provides crucial insights into lattice orientation, domain structure, and crystalline quality.
• This technique offers a high-throughput solution for evaluating non-centrosymmetric materials, advancing their application in electronics, photonics, and quantum technologies.