Integrated LED and Photodetector on Shared Substrate
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Solution Overview
Problem
In wireless optical communication systems and solid-state lighting, the integration of light emitting diodes (LEDs) and photodetectors on a single substrate faces challenges due to surface defects introduced by etching processes, which degrade photodetector performance and require additional filters to avoid cross-talk, increasing production costs and complexity.
Innovation Solution
The integration of a light emitting diode and a photodetector on a shared substrate, utilizing materials like indium gallium nitride (InGaN) for LEDs and gallium nitride (GaN) Schottky barrier photodetectors, which are formed using standard semiconductor processes, ensuring compatibility and minimizing defects while maintaining the sensitivity of LEDs, and employing visible-blind properties to avoid filter requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LEDs and photodetectors are integrated on a shared substrate, then device functionality and productivity are improved, but surface defects from etching processes degrade photodetector performance
Solution Approach 1:
The patent divides the substrate into distinct regions with different etching conditions. The LED region undergoes standard etching processes, while the photodetector region is protected or subjected to modified etching to preserve surface quality. This segmentation allows both components to coexist on the same substrate without mutual interference, resolving the contradiction between integration benefits and photodetector performance degradation.
Solution Approach 2:
Different surface quality requirements are applied to different locations on the substrate. The photodetector region maintains high surface quality with minimal defects, while the LED region tolerates standard etching-induced surface characteristics. This local quality differentiation enables successful integration while preserving photodetector sensitivity and performance.
2Object-affected harmful factors
If additional filters are added to avoid cross-talk between LED and photodetector, then signal interference is reduced, but production costs and device complexity increase
Solution Approach 1:
The patent extracts the photodetector from the LED's optical environment by positioning it in a region where LED light does not reach, or by using wavelength-selective materials that allow the photodetector to respond to its target wavelength while being insensitive to LED emission wavelengths. This eliminates the need for additional filtering components, reducing device complexity while preventing cross-talk interference.
Solution Approach 2:
The patent changes the operational parameters of the photodetector, specifically its spectral response characteristics, to match the communication wavelength while being blind to LED emission wavelengths. By adjusting the photodetector's sensitivity parameters through material selection or structural design, cross-talk is prevented without requiring physical filters, thus simplifying the device while eliminating harmful interference.
3Ease of manufacture
If standard semiconductor processes are used for integration, then manufacturing ease is improved, but surface defects are introduced that require additional processing
Solution Approach 1:
The patent applies preliminary protective measures to the photodetector region before standard etching processes are applied to the LED region. This may include depositing protective layers, applying masks, or pre-treating the photodetector area to make it resistant to etching-induced surface defects. After the LED fabrication is complete, the protective measures are removed, revealing a photodetector with minimal surface defects. This preliminary action enables use of standard semiconductor processes while preserving photodetector surface quality.
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 configuration achieves high responsivity and efficiency, allowing the integrated device to function effectively as both a transmitter and receiver with reduced production costs and simplified manufacturing, capable of operating under low illumination conditions without interference from LED emissions.
Implementation Method 1
a light emitting diode formed on the substrate
Implementation Method 2
Light emitting diodes (LEDs) may be used as optical transmitters
Implementation Method 3
an optical receiver to transform incident light into a detectable signal
Data Source
AI summary
The present application relates generally to light emitting diodes and photodetectors as well as their methods of manufacture and use. In one exemplary embodiment, an integrated device may include a substrate, a light emitting diode formed on the substrate, and a photodetector formed on the substrate. In another embodiment, a device may include a light emitting diode formed on a substrate, and the light emitting diode may act as both a solid state light and as an optical transmitter.