Photodetector Chip Top Layer Filtering for Ambient Light Rejection
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Solution Overview
Problem
Existing photodetector chips, particularly those based on InGaAs material, have high responsivity to wavelengths less than 1300 nm, leading to interference from ambient light and inaccurate distance detection in proximity sensors.
Innovation Solution
Incorporating a filter layer to block wavelengths less than 1300 nm and allow only wavelengths greater than or equal to 1300 nm to pass through, using a photodetector chip structure with a first electrode, substrate, light absorption layer, top layer, and second electrode, optimized for reduced responsivity to ambient light and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional photodetector chip is used, then the device can detect light signals, but the distance detection accuracy is low due to interference from ambient light with wavelengths less than 1300 nm
Solution Approach 1:
The photodetector chip structure is segmented into multiple functional layers: a first electrode, substrate, light absorption layer, top layer, and second electrode. This segmentation allows different layers to perform specific functions, with the top layer specifically designed to filter ambient light while the light absorption layer detects the detection signal, thereby resolving the contradiction between detecting light signals and rejecting ambient light interference.
Solution Approach 2:
Different layers of the photodetector chip are assigned different optical properties tailored to their specific functions. The top layer has optical properties optimized for blocking wavelengths less than 1300 nm, while the light absorption layer has properties optimized for absorbing wavelengths greater than or equal to 1300 nm. This local quality differentiation enables the chip to simultaneously achieve ambient light rejection and detection signal sensitivity.
2Adaptability or versatility
If the photodetector chip has high responsivity to wavelengths less than 1300 nm, then it can detect a broader range of light signals, but it becomes more susceptible to ambient light interference
Solution Approach 1:
The spectral detection range is segmented across different layers: the top layer handles wavelengths less than 1300 nm by blocking them, while the light absorption layer handles wavelengths greater than or equal to 1300 nm by absorbing them. This segmentation allows the photodetector to maintain high adaptability for detecting relevant signals while eliminating susceptibility to ambient light in the blocked wavelength range.
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
The solution achieves reduced interference from ambient light, enhancing the accuracy of distance detection in proximity sensors by filtering out wavelengths less than 1300 nm and allowing only relevant wavelengths to be detected.
Implementation Method 1
the first part has a thickness of 2.0 μm ̃6.0 μm to absorb a signal with a wavelength less than 1300 nm and allow a detection signal with a wavelength greater than or equal to 1300 nm to pass through
Data Source
AI summary
Provided are a photodetector chip, a proximity sensor, and an electronic device. The photodetector chip includes a first electrode, a substrate, a light absorption layer, a top layer, and a second electrode. The substrate is on one side of the first electrode. The light absorption layer is at one side of the substrate away from the first electrode. The top layer is at one side of the light absorption layer away from the substrate. The photodetector chip has an active region, the active region allows a detection signal to pass through, the top layer includes a first part corresponding to the active region, the first part has a thickness of 2.0 μm˜6.0 μm to absorb a signal with a wavelength less than 1300 nm and allow a detection signal with a wavelength greater than or equal to 1300 nm to pass through to reach the light absorption layer.