Photodiode Interlayer Reduces Dark Current
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Solution Overview
Problem
Photodiodes with germanium substrates face challenges in reducing dark current, which degrades their performance and accuracy, as existing methods like chemical processing and doping are either ineffective or costly and complex.
Innovation Solution
Incorporating an interlayer into selected portions of the electrode layer of the photodiode, specifically using materials like TiO2 to minimize conduction band offset and enhance the hole Schottky barrier height, thereby reducing dark current without compromising photocurrent collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If chemical processing is performed on the substrate to remove dark current, then dark current is reduced, but photocharge collection capability deteriorates
Solution Approach 1:
The patent applies different treatments to different regions of the photodiode structure. An interlayer is selectively formed only in the electrode layer at specific contact regions, while other regions maintain their original properties. This localized modification reduces dark current at contact points without affecting the photocharge collection capability in the active region.
Solution Approach 2:
The interlayer acts as an intermediary substance between the electrode and the semiconductor substrate. This intermediate layer modifies the interface properties to reduce dark current while maintaining or improving the overall device performance. The interlayer serves as a mediator that reconciles the conflicting requirements of dark current reduction and photocharge collection.
2Object-generated harmful factors
If doping methods are used to reduce dark current, then dark current is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the structural parameter of the device by introducing an interlayer with specific material properties (bandgap, thickness) rather than changing the chemical composition through doping. This parameter change approach achieves dark current reduction through physical structure modification, avoiding the complex multi-step doping processes required by conventional methods.
3Object-generated harmful factors
If an interlayer is inserted into the electrode layer, then dark current is reduced, but device structure becomes more complex
Solution Approach 1:
The interlayer is not formed throughout the entire device but only in specific portions of the electrode layer where it is most needed for dark current reduction. This partial application approach minimizes the structural complexity addition while achieving the primary goal of dark current suppression in critical regions.
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 approach significantly reduces dark current while maintaining or improving photodiode performance, offering simpler and cost-effective manufacturing compared to traditional doping methods, with the interlayer thickness influencing the extent of dark current reduction.
Implementation Method 1
enhance the hole Schottky barrier height
Implementation Method 2
minimize conduction band offset
Implementation Method 3
A photodiode is a semiconductor device that converts an optical signal into an electrical signal
Data Source
AI summary
A photodiode having a reduced dark current includes a semiconductor layer, a first contact part, a second contact part, and an active region. The first contact part disposed in a first region of the semiconductor layer includes an interlayer and at least one metal layer. The second contact part disposed in a second region of the semiconductor layer includes at least one metal layer. The active region is disposed between the first contact part and the second contact part. The first contact part and the second contact part are arranged asymmetrical to each other.