Raman Spectroscopy for Decoupling Temperature and Thermal Stress in 2D Films

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Solution Overview

Problem

Current methods for measuring temperature and thermal stress in nano-materials either suffer from contact-related errors or are limited to metal materials, failing to decouple the effects of temperature and stress on Raman shift signals, necessitating separate measurements.

Innovation Solution

A Raman spectroscopy method that differentiates between temperature and thermal stress by utilizing a two-dimensional film material with suspended and supported parts of varying stress states, establishing equations for Raman shift coefficients to simultaneously measure temperature and stress distributions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Raman spectroscopy is used to measure both temperature and stress, then non-contact measurement is achieved, but the temperature and stress are coupled to affect the Raman shift making it impossible to decouple their influences

Engineering Contradiction:

Improvemeasurement capabilityVSAvoiddecoupling complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The film material is divided into suspended and supported regions with different stress states. The suspended region experiences minimal stress while the supported region experiences substrate-induced stress. By comparing Raman shifts from these two regions, the temperature and stress contributions can be decoupled through mathematical subtraction of the stress effects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stress state parameter is changed by creating different boundary conditions (suspended vs. supported) in the same material. This allows the stress component of Raman shift to be isolated and subtracted, leaving only the temperature component for accurate temperature measurement.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If temperature and thermal stress are measured separately, then measurement simplicity is maintained, but simultaneous measurement capability is lost

Engineering Contradiction:

Improvemeasurement simplicityVSAvoidmeasurement efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The measurement process combines temperature and stress characterization into a single Raman spectroscopy experiment. By collecting Raman spectra from both suspended and supported regions simultaneously, both parameters can be extracted from one measurement session, improving efficiency while maintaining simplicity.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If contact methods are used for measurement, then measurement capability is achieved, but contact-related errors and restrictions to metal materials occur

Engineering Contradiction:

Improvemeasurement capabilityVSAvoidmaterial applicability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The contact-based mechanical measurement methods are replaced with non-contact Raman spectroscopy. This optical method uses laser excitation and spectral analysis instead of physical contact, eliminating contact-related errors and enabling measurement of non-metallic two-dimensional materials that cannot be measured by traditional contact methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables accurate, non-destructive, and non-contact simultaneous measurement of temperature and thermal stress in nano-materials, improving sensitivity and accuracy without complex calculations or additional assumptions, suitable for various two-dimensional film materials.

Implementation Method 1

Raman spectroscopy is reported as a non-contact method that can measure both the temperature and the stress

Methodology Applied

Scientific EffectRaman scattering:

Implementation Method 2

focusing a first laser beam on a surface of the suspended part... calculating a temperature rise of the two-dimensional film material generated at each of the different laser intensities

Methodology Applied

Scientific EffectOptical absorption heating: Absorption (EM radiation)

Data Source

PatentUS11137245B2Raman spectroscopy method for simultaneously measuring temperature and thermal stress of two-dimensional film material in situ

Publication Date: 2021.10.05 TSINGHUA UNIVERSITY

AI summary

Provided is a Raman spectroscopy method for simultaneously measuring a temperature and a thermal stress of a two-dimensional film material in situ. The method includes: providing the two-dimensional film material including a suspended part and a supported part and measuring Raman signals of the suspended part and the supported part; establishing equations of a Raman shift with temperature and a Raman shift with thermal stress for each of the suspended part and the supported part, and solving simultaneous equations to obtain coefficients with temperature and thermal stress; and scanning a characteristic Raman spectrum field of the two-dimensional film material and obtaining a temperature distribution and a thermal stress distribution of the two-dimensional film material according to the characteristic Raman spectrum field in combination of the coefficients of the Raman shift with temperature and the Raman shift with thermal stress.