Multi-Temperature Photoluminescence for Semiconductor Light-Emitter Quality
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Solution Overview
Problem
Existing methods for evaluating the luminous efficiency of semiconductor light-emitting devices with nitride-based compound semiconductor layers are inaccurate due to energy band bending caused by internal strain, leading to inconsistent performance and increased costs.
Innovation Solution
A method involving the formation of a multi-layered semiconductor film on a substrate, followed by photo-excitation and light emission intensity measurement at multiple temperature points to assess the active layer's quality, ensuring precise evaluation of internal quantum efficiency and selective excitation of the active layer without energy band bending interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If luminous efficiency is evaluated by measuring attenuation time of light emission at a single temperature point, then the evaluation process is simple and fast, but the measurement precision is insufficient due to energy band bending caused by internal strain
Solution Approach 1:
The patent introduces temperature as an additional dimension for evaluation by performing photoluminescence measurements at multiple temperature points (e.g., 77K and 300K). This multi-dimensional approach allows differentiation between effects caused by internal strain and those caused by carrier concentration, thereby resolving the measurement inaccuracy without significantly complicating the evaluation process
Solution Approach 2:
The patent changes the temperature parameter during measurement to obtain different photoluminescence characteristics. By measuring at multiple temperature points, the method can distinguish between strain-induced band bending and carrier concentration effects, enabling accurate luminous efficiency evaluation while maintaining process simplicity
2Measurement precision
If internal strain is present in multi-layered semiconductor film, then piezoelectric field is generated affecting active layer performance, but the existing evaluation method cannot precisely measure luminous efficiency due to energy band bending
Solution Approach 1:
By introducing temperature as an additional measurement dimension, the patent enables separation of strain effects from carrier concentration effects. The multi-temperature photoluminescence measurement reveals characteristic patterns that allow accurate luminous efficiency evaluation even in the presence of piezoelectric field-induced energy band bending
Solution Approach 2:
The patent uses the temperature-dependent photoluminescence characteristics as feedback to evaluate whether internal strain is affecting the active layer. By comparing measurements at different temperatures, the method can identify and compensate for energy band bending effects, providing accurate luminous efficiency data despite the presence of harmful piezoelectric fields
3Productivity
If wafer is processed without preliminary quality evaluation, then manufacturing cost is reduced and process is simplified, but productivity is lowered due to inability to identify high-performance devices
Solution Approach 1:
The patent performs preliminary photoluminescence evaluation at multiple temperature points before final device fabrication. This early assessment identifies wafers with high luminous efficiency, allowing selective processing of only the most promising candidates, thereby improving overall productivity without requiring complex real-time monitoring during fabrication
Solution Approach 2:
By using multi-temperature photoluminescence measurement as a preliminary screening tool, the patent can accurately identify high-performance active layers before committing to expensive and time-consuming fabrication processes. This parameter-based evaluation method ensures that only wafers meeting performance criteria proceed to manufacturing, optimizing resource allocation and productivity
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 approach allows for the efficient fabrication of semiconductor light-emitting devices with performance exceeding standards at reduced costs by ensuring high internal quantum efficiency and improved productivity through precise evaluation and quality control.
Implementation Method 1
performing pass/fail judgment of the active layer by photo-exciting the active layer in the wafer and then measuring intensity of light emission from the active layer
Implementation Method 2
measuring intensity of light emission from the active layer at least at two temperature points
Data Source
AI summary
A fabricating method of a semiconductor light-emitting device includes the step of forming a wafer including a multi-layered semiconductor film epitaxially grown on a base substrate and containing an active layer, the step of performing pass/fail judgment of the active layer by photo-exciting the active layer in the wafer and by measuring emission intensity from the active layer at least at two temperature points, and the step of forming a light-emitting device structure with the multi-layered semiconductor film containing the active layer judged to be of good quality in the pass/fail judgment.