Plan-view transmission electron microscopy specimen preparation for atomic layer materials using a focused ion beam...

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Focused ion beam (FIB) is a common technique for preparing transmission electron microscopy (TEM) specimens of 2D atomic layer materials.
• Conventional FIB preparation methods can cause ion-beam damage and hydrocarbon contamination to sensitive atomic layers.
• Existing methods like chemical etching and polymer adhesion also introduce potential artifacts.

Purpose of the Study:

• To develop a novel FIB specimen preparation method for 2D atomic layer materials.
• To protect delicate atomic layers from ion-beam bombardment and re-deposition during FIB milling.
• To enable high-quality structural analysis of materials like graphene and molybdenum disulfide (MoS2).

Main Methods:

• Development of a "microcapsule" technique to insulate the sample surface during FIB preparation.
• Utilizing scanning electron microscopy (SEM) in a dual-beam FIB-SEM for precise area localization.
• Application of the method to prepare plan-view TEM specimens of graphene and MoS2 atomic layers.

Main Results:

• Successful preparation of plan-view TEM specimens of graphene and MoS2 atomic layers with minimal damage.
• Obtained useful electron diffraction results revealing interlayer orientation relationships.
• Auger electron spectroscopy confirmed the absence of surface contamination after preparation.

Conclusions:

• The proposed "microcapsule" method effectively protects 2D atomic layer materials during FIB specimen preparation.
• This technique overcomes limitations of conventional methods, reducing ion-beam damage and contamination.
• The method facilitates detailed structural and orientational analysis of advanced 2D materials.