Silicon Carbide Avalanche Photodiode Guard Ring Design
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Solution Overview
Problem
Existing ultraviolet radiation detectors face challenges in achieving high sensitivity and high fill-factor detection due to the limitations of mesa structures, which hinder efficient detection of limited ultraviolet photons.
Innovation Solution
A silicon carbide avalanche photodiode with a PNI junction and a guard ring structure, where the guard ring laterally surrounds the anode region, allowing for efficient lateral confinement of the electrical field and reducing edge breakdown, enabling high fill-factor detection and low breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mesa structure is used to achieve lateral confinement of the electrical field, then low dark current is obtained, but high-fill-factor detection cannot be achieved
Solution Approach 1:
The device is segmented into distinct functional regions: a mesa structure for lateral confinement and a planar detection region for high fill-factor detection. The mesa structure is laterally separated from the main detection area, allowing each segment to optimize its specific function without compromising the other.
Solution Approach 2:
An intermediary structure (isolation layer and isolation groove) is introduced between the mesa structure and the detection region. This intermediary element allows the electrical field to be confined laterally by the mesa while preventing direct interference with the planar detection area, thus enabling both low dark current and high fill factor.
2Reliability
If a mesa structure is used for lateral confinement, then low dark current is achieved, but device complexity increases
Solution Approach 1:
The lateral confinement function is extracted from the main detection structure and implemented as a separate mesa structure. This extracted component can be optimized independently for low dark current while the main detection region maintains a simple planar geometry for high fill factor, thereby reducing overall device complexity.
Solution Approach 2:
Different structural qualities are applied locally: the mesa structure provides strong lateral confinement with vertical sidewalls in specific regions, while the detection region maintains a flat, simple planar structure. This localized application of structural complexity only where needed minimizes overall device complexity while achieving the desired performance.
3Measurement precision
If the anode region extends deeply into the body, then detection sensitivity improves, but breakdown voltage increases
Solution Approach 1:
The solution moves from a purely vertical extension of the anode region to a lateral extension approach. The anode region is extended laterally in the plane of the semiconductor body rather than deeply in the vertical direction, maintaining good detection sensitivity through lateral collection while keeping the vertical electric field distribution favorable for low breakdown voltage.
Solution Approach 2:
The doping concentration and geometric dimensions of the anode region are optimized to achieve the right balance. By adjusting these parameters, the anode region can extend sufficiently to collect carriers for high sensitivity while the electric field distribution is maintained at levels that prevent premature breakdown.
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 enables high sensitivity and low breakdown voltage, facilitating Geiger mode operation and improved optical response with reduced dead area, allowing for efficient detection of ultraviolet radiation.
Implementation Method 1
avalanche photodiode for detecting ultraviolet radiation
Implementation Method 2
avalanche photodiode
Data Source
AI summary
An avalanche photodiode for detecting ultraviolet radiation, including: a silicon carbide body having a first type of conductivity, which is delimited by a front surface and forms a cathode region; an anode region having a second type of conductivity, which extends into the body starting from the front surface and contacts the cathode region; and a guard ring having the second type of conductivity, which extends into the body starting from the front surface and surrounds the anode region.