研究目的
To demonstrate a systematic study on laser-assisted He+ milling on monolayer graphene samples, enabling ion milling by mitigating carbon contamination with in situ pulsed laser.
研究成果
The study successfully demonstrated laser-assisted He+ milling on monolayer graphene with sub 10 nm resolution, enabling complex nanoscale kirigami patterns. This technique opens possibilities for direct writing complex features on suspended membranes for various applications.
研究不足
The study notes the challenge of carbon redeposition near the milled area, which complicates achieving atomic resolution imaging of the lattice damage.
1：Experimental Design and Method Selection
The study involved using a helium gas field ion source for higher milling resolution on monolayer graphene, with a pulsed laser to mitigate carbon deposition.
2：Sample Selection and Data Sources
Commercial grade monolayer graphene samples on holey Si3N4 TEM membranes were used.
3：List of Experimental Equipment and Materials
Zeiss ORION NanoFab He/Ne ion microscope, prototype laser delivery system by Waviks, Inc., Nion Ultra STEM US200.
4：Experimental Procedures and Operational Workflow
Patterns were exposed with a constant pixel spacing of 0.25 nm and the linear dose from 1 × 104 to 5 × 105 ions/nm. Laser conditions were controlled with forward current ranging from 100 mA to 3 A, frequency from 10 to 3000 Hz, pulse width from 1 μs to 1 ms, and duty cycles from 0.01% to 3%.
5：Data Analysis Methods
Finite element method (FEM) simulation was conducted for heating analysis. STEM characterization was performed to analyze the milled areas.
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