Quantum Dot Photodetector Filtration for Lower Dark Current
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Solution Overview
Problem
Existing photodetectors face challenges in reducing dark current and achieving high manufacturing yield, particularly when using quantum dots due to the formation of soft aggregates that cause unevenness in the semiconductor film.
Innovation Solution
A method involving the filtration of a quantum dot dispersion liquid with specific parameters, including a pore diameter of less than 0.45 µm and the use of certain materials and ligands, followed by forming a semiconductor film on a first electrode and a second electrode, specifically using a sputtering method for the second electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If quantum dot dispersion liquid is used to form semiconductor film, then the photodetector can be manufactured, but soft aggregates form causing unevenness in the semiconductor film which increases dark current
Solution Approach 1:
The quantum dot dispersion liquid is filtered before being used to form the semiconductor film. This preliminary filtration action removes soft aggregates and impurities from the dispersion liquid, preventing them from being incorporated into the semiconductor film during the subsequent coating process, thereby ensuring film uniformity and reducing dark current.
Solution Approach 2:
A filter is introduced as an intermediary component between the quantum dot dispersion liquid and the semiconductor film formation process. The filter acts as a mediator that selectively removes harmful soft aggregates while allowing the quantum dots and necessary components to pass through, enabling the formation of a uniform semiconductor film with reduced dark current.
2Object-generated harmful factors
If filtration is applied to quantum dot dispersion liquid, then dark current is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent specifies particular parameters for the filtration process, including pore diameter range (0.01 µm to 1 µm) and filter material composition. By optimizing these parameters, the filtration step achieves effective dark current reduction while maintaining reasonable manufacturing complexity. The specified parameters ensure that the filter removes harmful aggregates without requiring excessively complex filtration systems.
3Manufacturing precision
If pore diameter of filter is less than 0.45 µm, then soft aggregates are suppressed, but manufacturing difficulty increases
Solution Approach 1:
The patent specifies a pore diameter range of 0.01 µm to 1 µm for the filter, with particular emphasis on filters having pore diameter less than 0.45 µm to effectively suppress soft aggregates. This parameter specification balances film uniformity requirements with manufacturing feasibility, as the defined range achieves the necessary filtration effectiveness without requiring extremely fine filters that would be difficult to manufacture and operate.
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 effectively suppresses the formation of soft aggregates, leading to a photodetector with reduced dark current and improved manufacturing yield.
Implementation Method 1
filtering a quantum dot dispersion liquid containing quantum dots having a maximal absorption in terms of absorbance in a wavelength range of 900 to 1700 nm, a ligand, and a solvent
Implementation Method 2
quantum dots having a maximal absorption in terms of absorbance in a wavelength range of 900 to 1700 nm
Implementation Method 3
the second electrode is formed on the semiconductor film by a sputtering method
Data Source
AI summary
A method for manufacturing a photodetector and a method for manufacturing an image sensor includes forming a first electrode on a support; filtering a quantum dot dispersion liquid containing quantum dots having a maximal absorption in terms of absorbance in a wavelength range of 900 to 1700 nm, a ligand, and a solvent, and forming a semiconductor film containing quantum dots on the first electrode by using the filtered quantum dot dispersion liquid; and forming a second electrode on the semiconductor film.