High property control of defects in 2D materials

The assignment of features and functions of two-dimensional (2D) materials is closely related to defect engineering. Conventional techniques, especially in non-vacuum spaces, do not provide the control required to integrate and investigate defects in 2D materials.

​​​​​​the study: Infrared light–matter interaction enhancement for a deterministic and tunable nanomechanical mechanism for hexagonal boron nitride.. Image Credit: Quality Stock Arts / Shutterstock.com

A recent study published in the journal nano messages He focuses on this issue by enhancing the light-matter interaction for hexagonal boron nitride (hBN) piezo nanoprocessing using atomic force microscopy (AFM). The research also investigates lattice distortions stimulated using nanoscale infrared spectroscopy.

Engineering defects in two-dimensional materials: an overview and applications

The importance of two-dimensional (2D) materials has greatly increased from a theoretical and practical perspective due to the remarkable electrical properties of two-dimensional graphene, transition-metal chalcogenides and hexagonal boron nitride (hBN).

The impact of these materials on the functionality of energy storage systems has been demonstrated over the past decade. As in the case of engineering faults in hBN and defective evolution of graphene, innovative features and functions can be added to 2D materials while preserving their combinatorial advantages using nanomachines.

Nanomachining provides new technologies for building 2D materials for optoelectronic devices, catalyst support, and quantum communications applications. Carefully selected hBN defects show quantum behavior at ambient temperature, providing a new framework for complex 2D quantum equipment.

Recently developed theoretical approaches predict that nanomachines cause highly interconnected electronic systems to be introduced into hBN. In this regard, structural distortions must be generated and tuned at specific points when processing 2D layers experimentally.

Limitations of Current Defect Engineering Techniques

Defects in hBN, other than those that occur naturally by surface modification, are usually made by ion implantation, exposure to electronic radiation, mechanical refining or heat treatment. These energy-intensive nanomachine methods create surface defects and impede in-depth analysis of certain features.

In addition, standard diagnostic techniques such as spectrophotometry, mass spectrometry, and X-ray photoluminescence spectroscopy are used to assess the response of induced defects.

These methods provide average data about the investigated volume, which covers a large area of ​​undisturbed material. However, these methods are currently unable to differentiate the fingerprint of a localized defect and its effect on the local properties of the metal.

Equipment with nanoscale analysis power, such as transmission electron microscopy (TEM), is usually difficult to use for on site Laboratory tests of two-dimensional structures. TEM provides an ultra-high-resolution image of the material’s crystal lattice. However, the chemical picture required to understand the local interactions that take place at the fault sites is not provided in the vacuum spectrometry performed in TEM.

Modern nanotechnology for defect engineering

Scanning probe microscopy (SPM) and other new methods have recently been established in nanomachines for engineering defects of 2D nanomaterials.

Breakthroughs in operational SPM, such as light-matter interaction and nanoscale infrared spectroscopy, enable the restricted formation of defects in 2D materials. However, few scientific studies have used nanoscale infrared spectroscopy to observe local chemical reactions at a catalytic site.

In this study, the researchers created and studied local nano-lattice defects in 2D materials using the photo-material interaction properties of atomic force microscopy (AFM) and nanoscale infrared spectroscopy.

The mechanism of light-matter interaction near the tip of the AFM has been studied, together with the effects of incident beam strength, exposure time, and environmental factors. Nano-infrared spectroscopy was used to characterize the modifications in chemical fingerprints associated with defect formation.

Main developments of the current study

It was discovered that nano-infrared spectroscopy can be used to effectively identify fingerprints for defects in 2D hBN wafers, such as wrinkles, angles and nanopores. The IR patterns accumulated by nano-infrared spectroscopy provide comprehensive data about the strain threshold of the lattice and the distortion caused by the perturbation of the nano-lattice.

In addition, the ability to alter the light-matter interaction at the tip of the AFM allowed the incorporation of defects into the hBN surface. This manipulation of the light-matter interaction provides a powerful strategy for defect engineering in other 2D materials, with temporal, structural and chemical effects that conventional defect techniques cannot match.

Based on these results, it is reasonable to conclude that the light-matter interaction and nanomachines approach based on nano-infrared spectroscopy used in this study can facilitate predictive control of chemical composition in 2D materials for applications such as optoelectronics and quantum detection.

reference

Torres Davila, FE et al. (2022). Infrared light–matter interaction enhancement for a deterministic and tunable nanomechanical mechanism for hexagonal boron nitride. nano messages. Available at: https://pubs.acs.org/doi/10.1021/acs.nanolett.2c02841

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