Light-Receiving Element Structure for Wider Depletion Layer Detection
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Solution Overview
Problem
Current light detectors face challenges in enhancing responsivity, particularly in extending the depletion layer to improve detection speed and accuracy, especially in applications like time-of-flight lidar devices where precise timing is critical.
Innovation Solution
The light detector design incorporates a semiconductor layer with specific conductivity types and impurity concentrations, including a third semiconductor region that contacts the fourth semiconductor region, allowing for a wider depletion layer extension and improved charge detection speed, along with a structure part with a different refractive index to enhance light concentration and reduce crosstalk noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the depletion layer is extended to improve detection speed and accuracy, then the responsivity of the light detector is improved, but the device complexity increases due to multiple semiconductor regions with different conductivity types and impurity concentrations
Solution Approach 1:
The light detector is divided into multiple semiconductor regions (first through fourth regions) with alternating conductivity types, where each region has specifically controlled impurity concentrations. This segmentation allows the depletion layer to extend across multiple interfaces, improving detection precision while maintaining manageable structural complexity through systematic design
Solution Approach 2:
Each semiconductor region is assigned specific local properties: the first and third regions have one conductivity type with higher impurity concentrations, while the second and fourth regions have alternating conductivity types with lower impurity concentrations. This local quality differentiation enables precise control of the depletion layer distribution to optimize detection performance
2Speed
If the time to detect charges as currents is shortened to improve responsivity, then the detection speed is improved, but the manufacturing precision requirements increase due to specific impurity concentration ratios
Solution Approach 1:
The invention specifies precise parameter ranges for impurity concentrations in each semiconductor region, with the first and third regions having higher concentrations and the second and fourth regions having lower concentrations. By defining these parameter ranges and their ratios, the patent enables faster charge detection while providing clear manufacturing guidelines to achieve the required precision
Solution Approach 2:
The alternating conductivity types and controlled impurity concentrations create multiple depletion layer interfaces that establish equipotential regions, facilitating faster charge carrier movement and collection. This design accelerates detection speed while the systematic parameter control provides a roadmap for manufacturing precision
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 responsivity of the light detector by shortening the time to detect charges as currents, improving detection accuracy and reducing jitter, thereby enhancing the performance of light detection systems, particularly in lidar devices.
Implementation Method 1
a light-receiving element; the light-receiving element includes a first semiconductor region, a second semiconductor region, a third semiconductor region, and a fourth semiconductor region
Implementation Method 2
The fourth semiconductor region has a lower first-conductivity-type impurity concentration than a first-conductivity-type impurity concentration of the semiconductor layer
Data Source
AI summary
A light detector includes a semiconductor layer and a light-receiving element. The semiconductor layer is of a first conductivity type. The light-receiving element includes a first semiconductor region, a second semiconductor region, a third semiconductor region, and a fourth semiconductor region. The first semiconductor region is of a second conductivity type. The second semiconductor region is located between the first semiconductor region and the semiconductor layer. The second semiconductor region is of the first conductivity type and contacts the first semiconductor region. The third semiconductor region is located between the second semiconductor region and the semiconductor layer. The third semiconductor region is of the second conductivity type. The fourth semiconductor region is located between the third semiconductor region and the semiconductor layer. The fourth semiconductor region is of the first conductivity type, and has a lower first-conductivity-type impurity concentration than a first-conductivity-type impurity concentration of the semiconductor layer.