All-Electric Spin FET Using Rashba Effect for Voltage-Controlled Spin Precession
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Solution Overview
Problem
Conventional spin field effect transistors face low spin injection efficiency and require external magnetic fields to control spin polarization, making them inefficient and complex.
Innovation Solution
An all-electric spin field effect transistor design using electrode pairs to generate electric fields that control electron spin polarization without ferromagnetic materials or external magnetic fields, utilizing a semiconductor heterojunction and quantum wire or nanowire structures to induce magnetic fields and manipulate electron spin direction through external voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferromagnetic materials and external magnetic fields are used to control spin polarization, then spin injection can be achieved, but spin injection efficiency is very low and device complexity increases
Solution Approach 1:
The patent extracts and eliminates ferromagnetic materials and external magnetic field requirements from the spin FET structure. Instead of using traditional ferromagnetic injection/detection nodes, the invention uses semiconductor heterojunctions with Rashba effect to achieve spin polarization and detection purely through electric fields, thereby removing harmful magnetic components and simplifying the device structure
Solution Approach 2:
The patent substitutes magnetic field-based spin control with electric field-based spin control. By utilizing the Rashba effect in semiconductor heterojunctions, the invention replaces the need for external magnetic fields and ferromagnetic materials with voltage-controlled electric fields, achieving spin polarization and detection through electrical means rather than magnetic means
2Ease of operation
If external magnetic fields are applied to change spin polarization direction, then electron spin direction can be controlled, but energy consumption increases and control precision decreases
Solution Approach 1:
The patent changes the control parameter from magnetic field strength/direction to electric field strength/direction. By applying voltage to the gate electrode, the electric field in the heterojunction channel is modulated, which directly controls the Rashba effect strength and thereby precisely controls spin polarization direction and electron spin precession without requiring external magnetic fields
Solution Approach 2:
The patent introduces the Rashba effect in semiconductor heterojunctions as an intermediary mechanism. The electric field from the gate electrode does not directly control spin direction but acts through the Rashba effect, which converts the electric field into spin-orbit coupling that controls electron spin precession, providing precise and energy-efficient spin control
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
Enhances spin injection efficiency and allows for precise control of electron spin polarization using external voltage, enabling effective on/off switching with significant current variation, up to five times the minimum current.
Implementation Method 1
According to the Rashba effect, when an electron passes through the injection node along a first direction, the electron spin will be polarized
Implementation Method 2
According to the Rashba effect, when the electron passes through the detection node along the first direction, the direction of electron spin will be detected
Implementation Method 3
these changes of the electric field will also change the equivalent magnetic field which affects the moving electrons (Rashba effect) and thus affects the precession speed of spin for electrons
Data Source
AI summary
An all-electric spin field effect transistor is disclosed, which includes an injection node, injecting an electron in a first spin direction; a detection node, detecting the electron in the first spin direction; and a gate, disposed between the injection node and the detection node such that the electron changes from the first spin direction to a second spin direction by carrying out precession; if the second spin direction is parallel to the first spin direction, the electron is able to pass through the detection node; if the second spin direction is antiparallel to the first spin direction, the electron is unable to pass through the detection node.