2D Material Nanosheets Laser Thinning Thickness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing two-dimensional material films face challenges in controlling thickness and achieving large areas, leading to restricted practical applications due to difficulties in material thickness control and small sample sizes.
Innovation Solution
A method utilizing high-energy nanosecond laser pulses to heat and sublimate layered samples protected by a PMMA coating, leveraging the difference in intralayer and interlayer heat transfer coefficients to achieve controlled thinning and large-area films with adjustable thickness, from single layers to hundreds of layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical exfoliation method is used, then two-dimensional layered materials can be obtained, but thickness cannot be controlled and transverse size is relatively small
Solution Approach 1:
The patent changes the preparation parameters by using chemical vapor deposition to grow large-area two-dimensional materials, then using laser irradiation parameters (power, pulse time, pulse number) to control the thickness. This allows independent control of area and thickness parameters that were coupled in mechanical exfoliation
Solution Approach 2:
The patent replaces the mechanical exfoliation method with a combination of chemical vapor deposition for growth and laser irradiation for thickness control. This substitution enables better control over both area and thickness parameters through chemical and optical processes rather than mechanical forces
2Area of moving object
If liquid phase exfoliation or chemical vapor deposition is used for large-area preparation, then area is improved, but thickness is still difficult to control
Solution Approach 1:
The patent introduces laser irradiation as an intermediary process between material deposition and final product. The laser acts as a mediator that selectively removes material layer by layer, enabling precise thickness control while maintaining large area. The PMMA coating serves as another intermediary that facilitates controlled ablation
Solution Approach 2:
The patent uses periodic laser pulsing to achieve controlled thickness reduction. By adjusting the pulse number, duration and power, the material is removed in controlled increments, allowing precise thickness control. The periodic action enables gradual thinning from thick deposits down to single-layer or few-layer structures
3Ease of manufacture
If existing preparation methods are used, then two-dimensional material films can be prepared, but thickness control is difficult, area is small and operation is complex
Solution Approach 1:
The patent employs a self-limiting ablation process where the laser irradiation automatically controls thickness through intralayer heat conduction. The heat diffusion within layers and across interfaces naturally limits the ablation depth, providing self-regulating thickness control without complex feedback systems. The process serves itself by using the material's own thermal properties to control the removal rate
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the rapid preparation of two-dimensional material films with controllable thickness and large areas, enhancing photoelectric properties and suitability for applications in sensors and nano-optoelectronic devices, with high thickness uniformity and simplified operation.
Implementation Method 1
use high-energy nanosecond laser pulses to heat and sublimate a layered sample
Implementation Method 2
When the applied temperature reaches the sublimation temperature of the material by intralayer conduction, thinning effect of one layer can be achieved
Implementation Method 3
heat and sublimate a layered sample protected by a polymethyl methacrylate (PMMA) coating
Data Source
AI summary
The present invention provides a two-dimensional material nanosheets with a large area and a controllable thickness and a general preparation method therefor. As an intralayer heat transfer coefficient of a two-dimensional material is much higher than an interlayer heat transfer coefficient thereof, the two-dimensional material is uniformly heated and sublimated layer by layer by controlling the energy of the laser pulses, a thinning thickness is controlled by adjusting the action time of the laser pulses, and finally, a two-dimensional material film with a controllable thickness is obtained. At the same time, a sample displacement stage moving freely in a two-dimensional plane space can realize preparation of the two-dimensional material film with a large area. Compared with traditional methods, the present invention can control a sample thickness of the two-dimensional material film, has a high generality, and is suitable for all kinds two-dimensional materials.