Photosensor Lateral Surface Encapsulation Reduces Leak Current
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Solution Overview
Problem
Conventional photosensors face issues such as increased lateral side leak current, dark current, and decreased photo response due to the etching process during semiconductor junction formation, and opaque electrodes that reduce the effective photo-sensing area.
Innovation Solution
A photosensor design featuring a semiconductor junction with a second polarity semiconductor layer that encapsulates the lateral surface, eliminating the need for an opaque electrode and reducing the impact of etching, comprising a base substrate, insulating layer, and a photodiode with a first and intrinsic semiconductor layer, and a second polarity semiconductor layer that encapsulates the lateral surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching process is used during semiconductor junction formation, then semiconductor junction can be formed, but lateral side leak current increases and photo response decreases
Solution Approach 1:
An insulating layer is introduced as an intermediary between the semiconductor junction and the environment. This insulating layer covers the lateral surface of the semiconductor junction, preventing direct exposure to etchants and eliminating lateral side leak current without requiring etching of the junction structure itself.
Solution Approach 2:
The patent extracts and eliminates the harmful etching process from the manufacturing sequence. By forming the semiconductor junction before applying the insulating layer, the need for subsequent etching is removed, thereby preventing lateral side leak current generation.
2Reliability
If opaque electrode is used to form semiconductor junction, then electrical connection is achieved, but effective photo-sensing area is reduced
Solution Approach 1:
The patent transitions from using opaque electrodes to transparent conductive electrodes. This change in optical property (from opaque to transparent) allows light to pass through the electrode layer, maintaining electrical connectivity while preserving the effective photo-sensing area and enhancing photo response.
Solution Approach 2:
The optical parameters of the electrode material are changed from opaque to transparent. By selecting transparent conductive materials and optimizing their thickness, the electrode maintains its electrical function while becoming optically transparent, thereby eliminating the trade-off between electrical connection and photo-sensing area.
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 design decreases lateral side leak current, dark current, and increases photo response, enhancing the effective photo-sensing area by avoiding the etching process's adverse effects and eliminating the need for opaque electrodes.
Implementation Method 1
a photodiode comprising a semiconductor junction on a side of the insulating layer away from the base substrate
Data Source
AI summary
A photosensor includes a base substrate; an insulating layer on the base substrate; and a photodiode including a semiconductor junction on a side of the insulating layer away from the base substrate. The semiconductor junction includes a first polarity semiconductor layer, an intrinsic semiconductor layer, and a second polarity semiconductor layer, stacked on the insulating layer. The second polarity semiconductor layer encapsulates a lateral surface of the intrinsic semiconductor layer.