Light Detection Element Using Ferromagnetic Layers

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Solution Overview

Problem

Current light detection elements using pn junctions of semiconductors face limitations in responsiveness and conversion accuracy, necessitating a more effective solution for converting light into electrical signals.

Innovation Solution

A light detection element comprising a magnetic element with a first and second ferromagnetic layer and a spacer layer, where the first ferromagnetic layer is irradiated with light intersecting the stacking direction, enhancing the conversion of light into electrical signals through changes in magnetization states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pn junction of a semiconductor is used for light detection, then the device can convert light into an electrical signal, but the responsiveness and conversion accuracy are limited

Engineering Contradiction:

Improveconversion accuracyVSAvoidresponsiveness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the fundamental detection parameter from electrical field interaction (pn junction) to optical field interaction (magnetization state). By using the magnetization state of the first ferromagnetic layer which changes in response to incident light, the system achieves both high responsiveness (direct optical-to-magnetic state conversion) and high conversion accuracy (magnetoresistive readout), resolving the contradiction between these two parameters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional semiconductor pn junction mechanism with a magnetic element mechanism. Instead of using charge carrier generation and separation in a pn junction, the system uses light-induced magnetization state changes in a ferromagnetic layer, which are then read out via magnetoresistance. This substitution enables superior responsiveness and accuracy while maintaining the light-to-electrical signal conversion function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a traditional light detection element is used, then the structure is simple, but the detection precision and responsiveness are insufficient

Engineering Contradiction:

Improvedetection precisionVSAvoidstructure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a composite magnetic element structure consisting of a first ferromagnetic layer, a nonmagnetic spacer layer, and a second ferromagnetic layer. This composite structure enables high detection precision through light-induced magnetization changes in the first ferromagnetic layer, while the overall device remains relatively simple compared to other high-precision detection methods. The composite material approach achieves enhanced performance without excessive structural complexity.

Inventive Principle:

Principle #40Composite materials

3Productivity

If a pn junction diode is used for light signal reception, then the device can function as a light sensor, but the conversion efficiency and sensitivity are limited

Engineering Contradiction:

Improveconversion efficiencyVSAvoidsensitivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent fundamentally changes the conversion parameter from electrical field-based charge separation (pn junction) to optical field-based magnetization modulation. The first ferromagnetic layer's magnetization state changes directly in response to incident light, providing high conversion efficiency. The subsequent magnetoresistive readout ensures high sensitivity, resolving the contradiction between conversion efficiency and sensitivity in traditional pn junction diodes.

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

The solution provides improved responsiveness and accuracy in converting light into electrical signals, enabling efficient light detection across various wavelengths, including infrared and ultraviolet, with high sensitivity and reliability.

Implementation Method 1

a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer interposed between the first ferromagnetic layer and the second ferromagnetic layer, in which the first ferromagnetic layer is irradiated with light in a direction intersecting a stacking direction of the magnetic element

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11703381B2Light detection element, receiving device, and light sensor device

Publication Date: 2023.07.18 TDK CORP

AI summary

Provided are a light detection element, a receiving device, and a light sensor device. The light detection element includes a magnetic element that includes a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer interposed between the first ferromagnetic layer and the second ferromagnetic layer, wherein the first ferromagnetic layer is irradiated with light in a direction intersecting a stacking direction of the magnetic element.