Varistor With Variable Thickness Insulator For Memory Effect
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Solution Overview
Problem
Existing electrically adjustable resistors lack the ability to vary resistance gradually and retain the last resistance value after the electrical voltage is stopped, limiting their application in signal limiting devices and neuromorphic systems.
Innovation Solution
A hybrid structure comprising a high critical temperature superconducting material and a ferroelectric material, where the ferroelectric material's polarization is modified by an electric field to change the doping state of the superconducting material, allowing for adjustable resistance with a memory effect, achieved through a stack with a conductive layer and an insulating layer varying in thickness to control the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hybrid structure with ferroelectric and superconducting materials is used to achieve resistance adjustment, then the resistance can be modified electrically, but the resistance cannot be varied gradually and cannot retain the last value after voltage cessation
Solution Approach 1:
The patent divides the ferroelectric layer into multiple regions with different thicknesses (d1, d2, d3, etc.) along the x-axis. Each region corresponds to a different resistance state of the superconducting layer beneath it. By applying voltage to specific segments, the resistance can be adjusted gradually in discrete steps rather than all-at-once, enabling progressive resistance variation while maintaining the hybrid structure's electrical adjustability
Solution Approach 2:
The patent introduces a spatial dimension (thickness variation along x-axis) to control the electric field distribution. The insulating layer's thickness varies continuously or in steps along the x-axis, creating different electric field intensities in different regions. This dimensional variation allows the system to achieve multiple resistance states and retain the last adjusted value, as different regions can be independently controlled to achieve gradual resistance variation
2Ease of manufacture
If a uniform thickness insulating layer is used, then the manufacturing is simpler, but the electric field distribution cannot be controlled to achieve gradual resistance variation
Solution Approach 1:
The patent applies local quality by making the insulating layer's thickness location-dependent. Different regions along the x-axis have different insulating layer thicknesses (d1, d2, d3, etc.), which creates locally different electric field intensities when voltage is applied. This allows precise control of the electric field in specific regions, enabling gradual resistance variation in the superconducting layer while maintaining a relatively simple overall structure that can be manufactured using standard thin-film deposition techniques
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
Enables continuous variation of resistance and retention of the last resistance value after voltage cessation, optimizing resistance switching and current blocking in neuromorphic systems and signal limiting devices.
Implementation Method 1
a second layer of a second ferroelectric material polarized or having a component of its polarization along a direction parallel to the direction of the stack
Implementation Method 2
an electric voltage control means between the first and the third layer, generating an electric field making it possible to modify the direction of polarization of the second material
Implementation Method 3
a first layer of a first superconducting material having a first under-doped state of first critical temperature and a second over-doped state of second critical temperature
Implementation Method 4
The orientation of the electric field of the second ferroelectric material induces either a lack of charge carriers in the first superconducting material, the first superconducting material being in an under-doped state or an excess charge carriers in the first superconducting material, the first superconducting material then being in an over-doped state
Implementation Method 5
the thickness of the fourth layer varying along a direction parallel to the x axis so as to vary the electric field applied between the third layer of the third conductive material and the first layer of the first superconductive material
Implementation Method 6
the adjustable resistance being configured to operate over a temperature range over which the electrical resistance difference between the over-doped state and the under-doped state of the first material is non-zero
Data Source
AI summary
The invention relates to a memory effect varistor comprising a multilayer containing a superconductive material (2) extending along an axis (x), a ferroelectric material (3) and a conductive third material (5). The varistor comprises a means (7) for controlling a voltage allowing an electrical field to be generated between the superconductive material (2) and the conductive material (5) allowing the polarisation direction of the ferroelectric second material to be modified. The varistor furthermore comprises an electrical insulator (6) arranged between the ferroelectric material (3) and the conductive material (5), the thickness of the insulator (6) varying along a direction parallel to the x-axis so as to make the electric field applied between the first layer (2) and the third layer (5) vary.