Stacked LED-Photodetector Pixel With Transparent Buried Electrode
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Solution Overview
Problem
Existing optoelectronic devices face a compromise between the sensitivity of the photon sensor and the emission efficiency of the light-emitting diode matrix, as the photodiode receives only a part of the incident light flux due to the buried electrode blocking the light path.
Innovation Solution
The optoelectronic device design includes a light-emitting diode with a buried electrode transparent to the detection wavelength, positioned between the photodetector and the interconnection stack, allowing increased detection area without reducing the buried electrode's lateral dimensions, and a conductive trench to connect the electrode to the control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the buried electrode dimensions are increased to improve light-emitting diode emission efficiency, then the emission efficiency is improved, but the photodetector sensitivity deteriorates because the electrode blocks more incident light flux
Solution Approach 1:
The patent changes the optical parameter (transparency) of the buried electrode at the detection wavelength. By selecting materials or structures that are transparent at the photodetector's detection wavelength, the electrode no longer blocks incident light flux, thereby resolving the contradiction between maintaining electrode functionality for light emission and allowing light transmission for detection.
2Measurement precision
If the detection area is increased to improve photodetector sensitivity, then the sensitivity is improved, but the light-emitting diode emission efficiency deteriorates due to reduced active area for light emission
Solution Approach 1:
The patent resolves the spatial conflict by transitioning to a three-dimensional stacked configuration. The photodetector and light-emitting diode are positioned at different vertical levels (z-dimension) rather than competing for the same lateral area. This allows the photodetector to have a larger detection area while the light-emitting diode maintains its emission area, as they operate in different spatial planes.
3Measurement precision
If the buried electrode laterally dimensions are reduced to allow more light to reach the photodetector, then the photodetector sensitivity is improved, but the light-emitting diode emission efficiency deteriorates
Solution Approach 1:
Instead of changing the lateral dimensions of the buried electrode, the patent changes its optical parameter (transparency) at the detection wavelength. This allows the electrode to maintain its original lateral dimensions for optimal light-emitting diode contact and emission efficiency, while simultaneously being transparent to the photodetector's detection wavelength, thus allowing maximum incident light flux to reach the photodetector.
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 enhances the photodetector's sensitivity by increasing the detected incident light flux without compromising the emission efficiency of the light-emitting diode.
Implementation Method 1
The buried electrode is transparent to the detection wavelength λ2
Implementation Method 2
a photodetector (210), sensitive to a detection wavelength λ2, passing through the light-emitting diode to reach a detection surface (211) of the photodetector
Implementation Method 3
a light-emitting diode with a buried electrode transparent to the detection wavelength
Data Source
Figure 1A~2A
Figure 2B~2C
Figure 2D~2E
AI summary
The invention relates to an optoelectronic device comprising a control circuit, a pixel comprising a photodetector, a light-emitting diode and an intermediate region interposed between the photodetector and the light-emitting diode. The photodetector is sensitive to a detection wavelength λ2. The light-emitting diode comprises an active stack with a cut-off wavelength λc less than λ2 and a buried electrode interposed between an interconnection stack of the circuit and the active stack, and covers a detection surface of the photodetector. The device further comprises a via passing right through the active stack, extending to the interconnection stack; an electrical contact passing right through the active stack, in contact with the buried electrode; an electrical path electrically connecting the buried electrode to the control circuit and comprising the through electrical contact and the via.The intermediate region is metal-free and the buried electrode is transparent to λ2.