Side-Edge NIR Spectrometry with Guard PIN Diode Noise Filtering
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Solution Overview
Problem
Existing silicon-based near infrared detectors are thick, allowing near infrared radiation to penetrate deeply and are prone to noise interference from visible light and ultraviolet radiation, which affects measurement accuracy.
Innovation Solution
A near infrared spectrometry device with multiple PIN diodes, a guard PIN diode, and floating guard rings to collect electron-hole pairs at specific absorption depths, shielded by external floating rings and metal contacts to filter out unwanted radiation, and use biasing circuits for fully depletion mode operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If silicon-based detectors are made thick to allow near infrared radiation penetration, then near infrared detection capability is improved, but visible light and ultraviolet noise increases
Solution Approach 1:
The detector is divided into multiple PIN diodes positioned at different depths within the silicon substrate. Each PIN diode is responsible for detecting near infrared radiation at its specific depth, creating segmented detection zones that allow selective measurement while reducing interference from other wavelengths
Solution Approach 2:
The patent transitions from traditional top-illumination detection to side-edge illumination detection. Near infrared radiation enters through the side edge of the silicon substrate and is detected by PIN diodes at specific depths, utilizing the depth dimension for wavelength discrimination while blocking unwanted radiation from the top surface
2Measurement precision
If multiple PIN diodes are positioned at different lateral positions corresponding to absorption depths, then wavelength-specific detection is improved, but device complexity increases
Solution Approach 1:
Multiple PIN diodes are merged into a single integrated silicon substrate structure, sharing common electrical connections and substrate infrastructure. This combining approach reduces the overall device complexity compared to using separate detector components while maintaining the ability to detect different wavelengths through depth-positioned diodes
3Measurement precision
If guard PIN diode and floating guard rings are added to collect and shield unwanted radiation, then measurement accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The guard PIN diode and floating guard rings are integrated directly into the detector structure, where they automatically collect and shield unwanted radiation without requiring external control systems or additional manufacturing steps. The structure serves its own shielding function through its inherent design
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
Enhances measurement accuracy by filtering out unwanted radiation and reducing noise, allowing precise detection of near infrared wavelengths.
Implementation Method 1
Each near infrared PIN diode of the different near infrared PIN diodes, once operated in a fully depletion mode, is configured to collect electron-hole pairs generated by radiation that passes through a side edge of the near infrared spectrometry device at a wavelength having an absorption depth that corresponds to a lateral position of the PIN diode
Implementation Method 2
The guard PIN diode is located at a lateral position that corresponds to a distance from the side edge that exceeds an absorption depth of unwanted radiation, wherein once operated in the fully depletion mode, the guard PIN diode is configured to collect electron-hole pairs generated by unwanted radiation that passed through the side edge of the near infrared spectrometry device and to prevent the electron-hole pairs generated by unwanted radiation to reach any of the different near infrared PIN diodes
Data Source
AI summary
A NIR spectrometry device that includes different NIR PIN diodes (NPDs) and a guard PIN diode (VLPD) that are operated in a fully depletion mode. The different NPDs are located at different lateral positions corresponding to absorption depths of different NIR wavelengths. Each NPD is configured to collect electron-hole pairs (EHPs) generated by radiation that passes through a side edge of the device at a wavelength having an absorption depth that corresponds to a lateral position of the NPD. The VLPD is located at a lateral position that corresponds to a distance from the side edge that exceeds an absorption depth of visible light. The VLPD is configured to collect EHPs generated by unwanted radiation that passed through the side edge of the NIR spectrometry device and to prevent the EHPs generated by unwanted radiation to reach any of the different NPDs.