Spin Polarization Transistor Using Circularly Polarized Light Control

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Solution Overview

Problem

Conventional spin polarization transistor elements face challenges in downsizing due to the need for space to arrange the gate electrode, limiting the freedom in arranging the source and drain components.

Innovation Solution

A spin polarization transistor element design that eliminates the need for a gate electrode by using circularly polarized light to control the spin direction in the channel layer, allowing for improved arrangement flexibility and downsizing, where the channel is bonded directly or through a tunnel layer with source and drain parts made of ferromagnetic materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a gate electrode is used to control spin direction in the channel layer, then the transistor can be operated, but the device size increases and arrangement freedom is restricted

Engineering Contradiction:

Improvetransistor operationVSAvoiddevice area

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The invention extracts and removes the gate electrode from the transistor structure, replacing it with circularly polarized light irradiation to control spin direction. This eliminates the need for the gate electrode and its associated voltage application mechanism, thereby reducing device area and improving arrangement freedom while maintaining transistor operation capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention substitutes the mechanical/electrical gate electrode control system with an optical control system using circularly polarized light. The light irradiation part replaces the gate electrode's function of controlling spin direction, transitioning from a physical contact-based control mechanism to a non-contact optical control mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a gate electrode is used to control spin direction, then voltage application is possible, but the voltage application mechanism becomes complex

Engineering Contradiction:

Improvevoltage applicationVSAvoidvoltage application mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention extracts and removes the gate electrode and its voltage application mechanism from the transistor structure. The gate electrode is replaced with a light irradiation part that controls spin direction through circularly polarized light, eliminating the complex voltage application mechanism while maintaining the ability to control transistor operation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention substitutes the electrical voltage application mechanism with an optical control mechanism. Instead of applying voltage through a gate electrode, the system uses circularly polarized light irradiation to control spin direction and transistor operation, simplifying the control mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 design enables the creation of a downsizable transistor structure with enhanced design freedom and simplified voltage application, allowing for efficient current flow between the source and drain without the need for a gate electrode, while maintaining switching speed comparable to current CMOS elements.

Implementation Method 1

a circularly polarized light irradiation part configured to irradiate the channel part with circularly polarized light for controlling a direction of spin of the channel part

Methodology Applied

Scientific EffectCircularly polarized light control: Magneto-Optic Effects

Implementation Method 2

the circularly polarized light irradiation part irradiates the channel part with the circularly polarized light, electrons with polarized spin are excited in the channel part, and electrical resistance of the channel part is changed

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 3

when the channel part is irradiated with the circularly polarized light, spin in the semiconductor material that forms the channel part can be transferred from a valence band to a conduction band

Methodology Applied

Scientific EffectBand gap excitation: Photoelectric Effect

Data Source

PatentUS9190500B2Spin polarization transistor element

Publication Date: 2015.11.17 THE JAPAN SCI & TECH AGENCY

AI summary

There are provided with a source part made of a ferromagnetic material magnetized in a first direction, a drain part made of a ferromagnetic material magnetized in the first direction, and separated from and arranged in parallel to the source part, a channel part arranged between the source part and the drain part, and bonded with the source part and the drain part directly or through a tunnel layer, and a circularly polarized light irradiation part that irradiates the channel part with circularly polarized light for controlling a direction of spin of the channel part.