Optical Sensor Layout With Confined Avalanche Breakdown
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Solution Overview
Problem
Existing optical sensing technologies face challenges in achieving high sensitivity and reducing dark current while maintaining a long detection distance, particularly in avalanche photodiodes and single-photon avalanche diodes.
Innovation Solution
The optical sensing apparatus incorporates a substrate with specific doping profiles and regions, including buried-dopant, interface-dopant, and punch-through regions, to control electric fields and confine avalanche breakdown, enhancing sensitivity and reducing dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If avalanche breakdown is allowed to occur in the absorption region, then sensitivity is improved, but dark current increases
Solution Approach 1:
The device is divided into distinct functional regions: an absorption region for generating photo-carriers and a separate punch-through region for confining avalanche breakdown. This segmentation allows the absorption region to maintain low dark current while the punch-through region provides the necessary avalanche multiplication for sensitivity enhancement.
Solution Approach 2:
Different regions of the device are given different doping characteristics tailored to their specific functions. The absorption region has doping optimized for carrier generation with low dark current, while the punch-through region has specific doping profiles that enable controlled avalanche breakdown. This local optimization resolves the contradiction between sensitivity and dark current.
2Length of moving object
If detection distance is extended, then sensitivity is improved, but signal strength decreases
Solution Approach 1:
The device utilizes changes in electric field parameters through controlled doping profiles in the punch-through region. By adjusting doping concentrations and depletion layer widths, the device optimizes the balance between extending detection distance and maintaining signal strength through enhanced avalanche multiplication in the dedicated punch-through region.
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 improves sensitivity and extends detection distance by confining breakdown to punch-through regions, thereby improving performance and reducing dark current in optical sensing devices.
Implementation Method 1
an absorption region including a second material different from the first material, the absorption region configured to receive an optical signal and generate photo-carriers in response to receiving the optical signal
Implementation Method 2
an amplification region formed in the substrate configured to collect at least a portion of the photo-carriers from the absorption region and to amplify the portion of the photo-carriers
Data Source
AI summary
An optical sensing apparatus is provided. The optical sensing apparatus including: a substrate including a first material; an absorption region including a second material different from the first material, the absorption region configured to receive an optical signal and generate photo-carriers in response to receiving the optical signal; an amplification region formed in the substrate configured to collect at least a portion of the photo-carriers from the absorption region and to amplify the portion of the photo-carriers carriers; a buried-dopant region formed in the substrate and separated from the absorption region, wherein the buried-dopant region is configured to collect at least a portion of the amplified portion of the photo-carriers from the amplification region; and a buffer layer formed between the buried-dopant region and the absorption region, wherein the buffer layer is intrinsic and has a thickness not less than 150 nm.