Imaging Device Electron Blocking Layer Pixel Crosstalk
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Solution Overview
Problem
Stacked typed imaging devices face challenges in reducing pixel size while maintaining sensitivity and preventing pixel crosstalk, as closely arranged pixels increase the likelihood of charge leakage between adjacent pixels.
Innovation Solution
The imaging device incorporates a configuration with photoelectric conversion elements having a first electrode, a second electrode, a photoelectric conversion layer, and an electron blocking layer with a specific surface potential change between 1 eV and 3 eV, and a distance of 250 nm or less between adjacent electrodes, which helps prevent pixel crosstalk and allows for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between adjacent pixel electrodes is reduced to increase pixel density, then the number of pixels and device miniaturization are improved, but pixel crosstalk increases due to charge leakage between adjacent pixels
Solution Approach 1:
A charge blocking layer is introduced as an intermediary between adjacent pixel electrodes. This layer is positioned at the bottom of the photoelectric conversion layer and selectively blocks charge carriers (electrons or holes) from leaking into adjacent pixels while allowing photogenerated charges to be collected by the pixel electrode. The charge blocking layer thus mediates between the need for close pixel spacing and the need to prevent charge leakage, enabling high pixel density without significant crosstalk.
2Productivity
If the pixel electrode size is reduced to increase pixel density, then the number of pixels is improved, but sensitivity deteriorates due to smaller charge collection area
Solution Approach 1:
The photoelectric conversion layer is segmented into regions associated with different pixel electrodes, with the charge blocking layer forming boundaries between these regions. This segmentation confines charge carriers to their respective pixel regions, ensuring that even small pixel electrodes can collect charges efficiently without loss to adjacent pixels. The segmentation thus preserves sensitivity despite reduced pixel electrode size by preventing charge leakage at the boundaries.
3Reliability
If spacing between adjacent pixel electrodes is increased to prevent pixel crosstalk, then pixel crosstalk prevention is improved, but device size increases and pixel density decreases
Solution Approach 1:
The charge blocking layer serves as a mediator that enables close spacing between pixel electrodes while preventing crosstalk. By positioning this blocking layer at the interface between adjacent pixels, the design eliminates the need for large spacing margins. The charge blocking layer actively prevents charge leakage across the boundary, allowing pixels to be packed densely without compromising crosstalk prevention, thus reducing overall device area while maintaining high reliability.
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 configuration achieves high sensitivity and enables the increase of pixel density while minimizing pixel crosstalk, allowing for both high sensitivity and device miniaturization.
Implementation Method 1
a photoelectric conversion layer that generates the charges in response to light incident on the photoelectric conversion layer
Implementation Method 2
a charge blocking layer that prevents charge injection from the electrode(s) into the photoelectric conversion layer
Data Source
AI summary
According to an aspect of the invention, an imaging device includes a plurality of photoelectric conversion elements and a read-out portion. The photoelectric conversion elements are arranged above a substrate. The read-out portion reads out signal corresponding to charges which are generated from each of the photoelectric conversion elements. Each of the photoelectric conversion elements includes a first electrode that collects the charge, a second electrode that is disposed opposite to the first electrode, a photoelectric conversion layer that generates the charges and disposed between the first electrode and the second electrode, and an electron blocking layer that is disposed between the first electrode and the photoelectric conversion layer. Distance between the first electrodes of adjacent photoelectric conversion elements is 250 nm or smaller. Each of the electron blocking layers has a change in surface potential of −1 to 3 eV from a first face to a second face.