Polycrystalline Semiconductor Crystal Structure Analysis
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Solution Overview
Problem
Current techniques for characterizing the crystalline structure of polycrystalline semiconductor materials, such as those used in photovoltaic cells, are cumbersome, destructive, and costly, making them unsuitable for mass production and in-situ testing due to requirements for sample preparation and high-resolution equipment.
Innovation Solution
A method involving the excitation of polycrystalline semiconductor materials to generate a luminescence signal, which is detected at varying polarization angles, with data modeled as a sum of sinusoids to estimate characteristic parameters like amplitude, phase shift, and frequency, allowing for non-destructive, rapid, and inexpensive characterization without sample preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning electron microscope (SEM) operating in EBSD mode or transmission electron microscope (TEM) is used to characterize the structure or microstructure of polycrystalline materials, then measurement precision is improved, but device complexity and ease of manufacture deteriorate due to difficult sample preparation requirements
Solution Approach 1:
The patent replaces mechanical sample preparation methods (polishing, sectioning) with optical excitation and luminescence detection. Instead of physically preparing the sample surface, the method uses light to excite the material and analyzes the emitted luminescence signal to characterize crystal structure, thereby eliminating the need for complex mechanical sample preparation while maintaining measurement precision
Solution Approach 2:
The patent changes the detection parameter from direct structural observation (requiring physical access to sample interior) to optical property measurement (luminescence polarization). By measuring how the luminescence signal polarizes at different angles, the method infers crystal structure information without requiring physical sample preparation, thus resolving the contradiction between precision and preparation complexity
2Measurement precision
If mapping polarized Raman spectra is used to characterize the structure or microstructure of polycrystalline materials, then measurement precision is improved, but loss of energy increases due to requirement of high spectral quality laser and very high resolution spectrometer
Solution Approach 1:
The patent employs standard, inexpensive components for luminescence excitation and detection rather than requiring high-end, energy-intensive Raman spectroscopy equipment. The method uses conventional light sources and detectors that are widely available and energy-efficient, achieving comparable structural characterization precision without the high energy costs of Raman systems
Solution Approach 2:
The patent extracts only the essential information needed for structural characterization from the luminescence signal (polarization characteristics) rather than requiring full spectral analysis. By focusing on polarization angle dependencies rather than complete Raman spectral mapping, the method reduces energy consumption while maintaining precision for crystal structure identification
3Ease of operation
If conventional luminescence analysis is used to detect defects in photovoltaic cells, then ease of operation is improved, but measurement precision deteriorates due to inability to provide detailed structural or crystalline microstructure information
Solution Approach 1:
The patent systematically varies the polarization angle of the luminescence detection in periodic steps (e.g., 0°, 45°, 90°, 135°) to extract crystal structure information. This periodic angular scanning maintains operational simplicity while providing precise structural characterization, as the systematic angle variation reveals crystallographic orientation and defect information that single-angle measurements cannot provide
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 simple, rapid, and cost-effective structural characterization of polycrystalline materials, suitable for mass production and in-situ testing, providing high spatial resolution and the ability to analyze materials during growth processes, thus improving quality control and compliance testing.
Implementation Method 1
exciting the material so as to generate the emission by the material of a luminescence signal
Implementation Method 2
optical excitation is used to generate by photoluminescence the luminescence signal emitted by the material
Implementation Method 3
detecting, at each point of a mesh of a predetermined spatial area of the material, the luminescence signal following a variable polarization angle
Data Source
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AI summary
A method for analysing the crystal structure of a polycrystalline semiconductor is described. According to one embodiment, it comprises exciting the semiconductor so as to make it emit a light signal at each point of a mesh in a preset spatial zone of the semiconductor; detecting the light signal as a function of variable polarisation angle, in a frequency band the width of which is larger than or equal to the width of the bandgap of the semiconductor; estimating, at each point of the mesh in the preset spatial zone of the semiconductor, a datum characterising the modulation of the light signal, which modulation is modelled by a sum of sinusoids, as a function of polarisation angle, on the basis of the signal detected for said point of the mesh; and displaying the characterising datum on all the points of the mesh in the preset spatial zone.