Dielectric Mediator for μ-PCD Crystalline Quality Evaluation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing microwave photoconductivity decay (μ-PCD) technique struggles to evaluate the crystalline quality of thin-film semiconductors, especially when an electrically conductive film is formed under the semiconductor, due to insufficient sensitivity and potential damage from high excitation light intensity, and is not effective for thin-film samples like polycrystalline or amorphous silicon.
Innovation Solution
A crystalline quality evaluation apparatus and method that uses a dielectric transparent to excitation light between the thin-film semiconductor and the electromagnetic wave emitting section, allowing for enhanced sensitivity and nondestructive evaluation by optimizing the thickness and permittivity of the dielectric to match the electromagnetic wave's wavelength, thereby improving signal intensity and power transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the intensity of excitation light is increased to enhance measurement sensitivity, then measurement sensitivity is improved, but the sample is likely to be damaged
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the electromagnetic wave emitting section and the thin-film semiconductor sample. This dielectric layer has optimized thickness and permittivity to enhance the electric field intensity in the semiconductor sample through constructive interference, thereby improving measurement sensitivity without requiring excessive excitation light intensity that would damage the sample.
Solution Approach 2:
The patent optimizes the thickness and permittivity parameters of the dielectric layer to achieve maximum electric field enhancement in the semiconductor sample. By carefully selecting these parameters, the system achieves high measurement sensitivity using lower excitation light intensity, preventing sample damage while maintaining accurate measurements.
2Adaptability or versatility
If the conventional μ-PCD technique is used on thin-film semiconductors with conductive films, then the existing method can be applied, but sufficient electric field intensity cannot be obtained and measurement becomes difficult
Solution Approach 1:
The dielectric layer serves as a mediator that enables the conventional μ-PCD technique to work effectively on thin-film semiconductors with conductive films. By positioning the dielectric layer between the electromagnetic wave source and the sample, it creates the necessary electric field enhancement that allows measurements on previously difficult-to-measure samples.
Solution Approach 2:
The patent modifies the measurement system by introducing a dielectric layer with specific thickness and permittivity parameters. This parameter optimization enables sufficient electric field intensity to be achieved in the semiconductor sample even when a conductive film is present, thereby extending the applicability of the μ-PCD technique to a broader range of samples.
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 and sensitive evaluation of crystalline quality in thin-film semiconductors even under electrically conductive films, with improved signal strength and reduced noise, allowing for noncontact and nondestructive measurement of crystalline quality in a short period.
Implementation Method 1
optimizing the thickness and permittivity of the dielectric to match the electromagnetic wave's wavelength, thereby improving signal intensity and power transmission efficiency
Implementation Method 2
optimizing the thickness and permittivity of the dielectric to match the electromagnetic wave's wavelength
Implementation Method 3
an electromagnetic wave is emitted to irradiate a semiconductor sample, thereby causing free electrons in the semiconductor sample to move (migrate) according to an electric field of the electromagnetic wave
Implementation Method 4
In the μ-PCD technique, an electromagnetic wave is emitted to irradiate a semiconductor sample
Implementation Method 5
emit excitation light having energy equal to or greater than a band gap of the above thin-film sample, to irradiate a small area of the thin-film sample, in a converging manner, thereby generating photo-excited carriers in the small area of the sample
Data Source
AI summary
The present invention provides a crystalline quality evaluation apparatus (1) and a crystalline quality evaluation method for thin-film semiconductors, which are designed to evaluate crystalline quality of a sample (2) of a thin-film semiconductor (2a) by emitting excitation light and an electromagnetic wave to irradiate a measurement site of the sample (2), and detecting an intensity of a reflected electromagnetic wave from the sample (2). In the present invention, the thin-film semiconductor (2a) of the sample (2) is formed on an electrically conductive film (2b), and a dielectric (3) transparent to the excitation light is additionally disposed between the sample (2) and a waveguide (13) for emitting the electromagnetic wave therefrom. Thus, the thin-film semiconductor crystalline quality evaluation apparatus (1) and method configured in this manner make it possible to evaluate the crystalline quality even in the above situation where the electrically conductive film (2b) is formed under the semiconductor thin-film (2a).