Light Detecting Element Electrode Reflectance Optimization
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Solution Overview
Problem
Existing stacked photoelectric conversion devices suffer from low light utilization efficiency due to the placement of a zinc oxide layer between the metal electrode layer and the photoelectric conversion layer, which prevents efficient use of light reflected by the pixel electrode.
Innovation Solution
A light detecting element is designed with a first electrode comprising a first metal layer and a second metal layer between the first metal layer and the photoelectric conversion film, along with an oxide layer formed from the oxide of the metal in the second metal layer, ensuring high reflectance and efficient light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zinc oxide layer is provided between the metal electrode layer and the photoelectric conversion layer, then the structure provides good electrical insulation and contact, but light reflected by the pixel electrode cannot be efficiently used, reducing light utilization efficiency
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a first metal layer for high reflectance, a second metal layer with controlled thickness (5-50 nm) for electrical contact while allowing light transmission, and an oxide layer for insulation. This segmentation allows each layer to optimize its specific function without compromising the others.
Solution Approach 2:
The thickness of the second metal layer is precisely controlled within 5-50 nm to achieve the optimal balance between electrical conductivity and optical transparency. This parameter optimization enables the layer to conduct electricity effectively while allowing reflected light to pass through to the photoelectric conversion layer.
2Use of energy by moving object
If a metal electrode layer with high reflectance is used, then light reflected by the pixel electrode can be efficiently used, but the contact resistance with the photoelectric conversion layer increases
Solution Approach 1:
The electrode is divided into a first metal layer (for reflectance) and a second metal layer (for electrical contact), with the oxide layer providing insulation between them. This segmentation allows the reflectance function and electrical contact function to be performed by different layers, resolving the contradiction.
Solution Approach 2:
The oxide layer acts as an intermediary between the metal layers and the photoelectric conversion layer, providing electrical insulation while allowing the metal layers to perform their optical and electrical functions. The second metal layer serves as an intermediary conductor that maintains good electrical contact without requiring direct contact between the high-reflectance metal and the photoelectric conversion layer.
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 configuration enhances light utilization efficiency and sensitivity of the photoelectric conversion device by effectively using reflected light, leading to improved performance in image sensors and similar applications.
Implementation Method 1
a reflectance at the first electrode with respect to light having a certain wavelength transmitted through the photoelectric conversion film is higher than a reflectance specific to a material forming the second metal layer with respect to light having the certain wavelength
Implementation Method 2
a light detecting element including a photoelectric conversion film is stacked over a semiconductor substrate
Data Source
AI summary
The disclosed light detecting element includes a first electrode, a second electrode, and a photoelectric conversion film arranged between the first electrode and the second electrode. The first electrode includes a first metal layer, a second metal layer arranged between the first metal layer and the photoelectric conversion film, and an oxide layer arranged between the second metal layer and the photoelectric conversion film and formed of an oxide of a metal that the second metal layer contains as a main component. The reflectance at the first electrode with respect to light having a certain wavelength transmitted through the photoelectric conversion film is higher than a reflectance specific to a material forming the second metal layer with respect to light having the certain wavelength.