Organic Imaging Element Oxide Stack for Afterimage Reduction

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Solution Overview

Problem

Current imaging elements face challenges in improving afterimage characteristics due to trap formation at the interface between the semiconductor layer and the photoelectric conversion layer, leading to reduced image quality and increased noise.

Innovation Solution

The implementation of a semiconductor layer with a stacked structure, where the first layer is formed using an oxide semiconductor material and the second layer is composed of indium (In), gallium (Ga), zinc (Zn), and tin (Sn) with specific composition ratios, which reduces oxygen elimination and trap occurrence at the interface, enhancing charge transport and afterimage characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional semiconductor layer is used between the electrode and photoelectric conversion layer, then the device structure is simple, but oxygen elimination occurs from the first layer and traps form at the interface, deteriorating afterimage characteristics

Engineering Contradiction:

Improveafterimage characteristicsVSAvoidsemiconductor layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The semiconductor layer is divided into a stacked structure with a first layer and a second layer having different compositions and functions. The first layer (In-Ga-Zn-O) provides stable oxygen retention, while the second layer (In-Sn-Zn-O) with high C5s value reduces trap formation at the interface with the photoelectric conversion layer. This segmentation allows each layer to address specific problems independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite oxide semiconductor materials with specific elemental compositions (In-Ga-Zn-O and In-Sn-Zn-O) to achieve desired properties. The composite structure combines materials with complementary characteristics: one layer for oxygen stability and another for interface quality, resolving the contradiction between simplicity and performance.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the semiconductor layer uses a single material, then the manufacturing process is simple, but trap formation occurs at the interface with the photoelectric conversion layer, reducing image quality

Engineering Contradiction:

Improveinterface qualityVSAvoidsemiconductor layer fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The semiconductor layer is segmented into two distinct layers with different material compositions. The first layer uses In-Ga-Zn-O oxide semiconductor material while the second layer uses In-Sn-Zn-O oxide semiconductor material with specific composition ratios. This segmentation enables precise control of interface properties to reduce trap formation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes material composition parameters by incorporating specific elements (In, Ga, Zn, Sn) in controlled ratios. The second layer is designed with a high C5s value (contribution ratio of 5s orbital to conduction band minimum) and specific oxygen deficiency generation energy (EVO > 3.0 eV), which are critical parameters for reducing trap formation at the interface.

Inventive Principle:

Principle #35Parameter changes

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 improves the afterimage characteristics by preventing oxygen elimination from the first layer and reducing trap formation, leading to better charge transport and reduced noise, thereby enhancing image quality.

Implementation Method 1

oxygen deficiency generation energy EVO larger than 3.0 eV

Methodology Applied

Scientific EffectOxygen deficiency generation energy:

Implementation Method 2

a value for C5 s indicating a contribution ratio of a 5 s orbital to a conduction band minimum larger than 0.4

Methodology Applied

Scientific EffectConduction band minimum and 5 s orbital contribution:

Implementation Method 3

has a band gap Eg larger than 3.0 eV

Methodology Applied

Scientific EffectBand gap:

Data Source

PatentUS20240355842A1Imaging element and imaging device

Publication Date: 2024.10.24 SONY SEMICON SOLUTIONS CORP

AI summary

An imaging element according to an embodiment of the present disclosure includes: a first electrode and a second electrode that are disposed in parallel; a third electrode that is disposed to be opposed to the first electrode and the second electrode; a photoelectric conversion layer that is provided between the first electrode and second electrode, and the third electrode, and includes an organic material; and a semiconductor layer including a first layer and a second layer that are stacked in order from side of the first electrode and the second electrode between the first electrode and second electrode, and the photoelectric conversion layer, in which the first layer includes a first oxide semiconductor material, the second layer includes a second oxide semiconductor material including indium (In), gallium (Ga), zinc (Zn), and tin (Sn), and a composition ratio of In, Ga, Zn, and Sn in the second oxide semiconductor material satisfies formulas (1), (2), and (3).