CIGS PN Junction Structure Without Selenization or Cd Buffer Layers
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Solution Overview
Problem
Conventional CIGS photodiode elements require selenization treatment and use Cd-containing buffer layers, which lead to defects, low open-circuit voltage, and inefficient photoelectric conversion.
Innovation Solution
A PN junction is developed using a p-type CIGS semiconductor thin film layer with a Cu to In molar ratio of 1.8 to 2 and an n-type CIGS semiconductor thin film layer with a Cu to In molar ratio of 1.1 to 1.2, eliminating the need for selenization treatment and replacing Cd-containing layers with Cd-free alternatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Pn junctions are used in CMOS image sensors, then the sensor can detect visible light, but the detection range is limited and near-infrared light cannot be effectively blocked
Solution Approach 1:
The patent uses a composite material structure consisting of a silicon-based semiconductor layer and a germanium-based semiconductor layer to form the Pn junction. This composite structure enables the sensor to block near-infrared light while maintaining visible light detection capability, resolving the contradiction between detection range and near-infrared blocking capability.
2Reliability
If a silicon-based semiconductor substrate is used, then the sensor has good visible light detection capability, but the near-infrared blocking performance is insufficient
Solution Approach 1:
The patent combines silicon-based and germanium-based semiconductor materials in a layered structure. The silicon-based layer provides excellent visible light detection, while the germanium-based layer adds near-infrared blocking capability, thus resolving the contradiction between visible light detection reliability and near-infrared blocking adaptability.
Solution Approach 2:
The patent applies different material properties to different regions of the semiconductor structure. The silicon-based region is optimized for visible light detection, while the germanium-based region is optimized for near-infrared absorption, allowing each region to perform its specialized function and resolving the contradiction between the two opposing requirements.
3Measurement precision
If the Pn junction structure is optimized for visible light detection, then detection sensitivity improves, but the ability to block near-infrared light deteriorates
Solution Approach 1:
The patent employs a composite semiconductor structure where the silicon-based layer is optimized for sensitive visible light detection while the germanium-based layer specifically absorbs near-infrared light. This composite approach allows the system to achieve high detection sensitivity for visible light while simultaneously blocking harmful near-infrared interference.
Solution Approach 2:
The patent implements local optimization by designing the silicon-based region with properties optimized for visible light sensitivity and the germanium-based region with properties optimized for near-infrared absorption. This spatial differentiation of material properties resolves the contradiction between detection sensitivity and near-infrared interference blocking.
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 proposed PN junction achieves higher photoelectric conversion efficiency and reduces defects, enabling effective carrier transportation and light absorption without the need for selenization or Cd-containing materials.
Implementation Method 1
a first doped region in the silicon-based semiconductor substrate, the first doped region being doped to be n-type; a second doped region in the silicon-based semiconductor substrate, the second doped region being doped to be p-type; wherein the Pn junction is formed between the first doped region and the second doped region
Implementation Method 2
the detection range of the CMOS image sensor can be blocked from near-infrared light, so that the detection precision of the CMOS image sensor can be improved
Data Source
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AI summary
The patent application relates to a PN junction as well as the preparation method and use thereof. Said PN junction comprises a p-type CIGS semiconductor thin film layer and an n-type CIGS semiconductor thin film layer, wherein the n-type CIGS semiconductor thin film layer comprises or consists essentially of elements Cu, In, Ga and Se, where the Cu to In molar ratio is within the range of 1.1 to 1.5, and has a chemical formula of Cu(InxGa1. x)Se2, where x is within the range of 0.6 to 0.9. The patent application further relates to a semiconductor thin film element comprising said PN junction, in particular a photodiode element, and a photoelectric sensing module comprising said semiconductor thin film element as well as the various uses thereof.