Orthogonal Ferroelectric Junction Structure for Stable 2-Bit Memory
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Solution Overview
Problem
Existing ferroelectric field-effect transistors (FeFETs) face limitations due to low-quality interfaces, charge traps, gate leakage, and non-uniform operational characteristics, which hinder their utilization in in-memory computing devices, and multi-state ferroelectric memory devices struggle with instability and non-uniformity in polarization states.
Innovation Solution
A junction structure element is developed with a first polarization layer polarized horizontally and a second polarization layer polarized vertically, each independently controlled by voltage, allowing for four distinct resistance states and enabling 2-bit memory implementation without intermediate polarization states, using materials like CuInP2S6 and SnS with an insulating h-BN layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If existing ferroelectric materials (oxide and perovskite) are used in FeFETs, then the device structure is simple, but the interface quality is low and charge traps occur
Solution Approach 1:
The patent uses a composite structure combining two-dimensional ferroelectric material (first polarization layer) with traditional semiconductor material (second polarization layer). This composite approach allows the device to benefit from the high interface quality and mobility of 2D materials while maintaining the functional advantages of conventional semiconductors, thereby resolving the contradiction between simple device structure and high interface quality.
2Quantity of substance
If intermediate polarization states are used to implement multi-state memory, then multiple memory states can be stored, but operational non-uniformity increases
Solution Approach 1:
The patent transitions from controlling polarization magnitude to controlling polarization direction. By using orthogonal polarization directions (horizontal for first layer, vertical for second layer) to represent different logic states, the system achieves multi-state memory functionality without relying on intermediate polarization magnitudes, thereby eliminating operational non-uniformity while maintaining multiple stable states.
3Device complexity
If single ferroelectric material is used as channel, then device structure is simple, but polarization control uniformity deteriorates
Solution Approach 1:
The patent divides the polarization control function into two separate layers: the first polarization layer (2D ferroelectric material) handles horizontal polarization control via source-drain voltage, while the second polarization layer (semiconductor material) handles vertical polarization control via gate voltage. This segmentation allows each layer to be optimized for its specific polarization direction, achieving uniform polarization control without increasing overall device structural complexity.
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 solution achieves independent control of polarization directions, enabling stable and efficient 2-bit memory operations with direct transitions between resistance states, overcoming the limitations of existing FeFETs and multi-state ferroelectric memory devices.
Implementation Method 1
a first polarization layer (101) containing a material having a ferroelectric characteristic of being polarized only horizontally
Implementation Method 2
a second polarization layer (102) disposed on the first polarization layer (101) and containing a material having a ferroelectric characteristic of being polarized only vertically
Implementation Method 3
an insulating layer (103) disposed between the first polarization layer (101) and the second polarization layer (102) and containing a material having non-dielectric and insulating characteristics
Data Source
AI summary
A junction structure element, a method of manufacturing the same, and an in-memory computing device including the same are disclosed. The junction structure element may include: a first polarization layer containing a material having a ferroelectric characteristic of being polarized only horizontally; a second polarization layer disposed on the first polarization layer and containing a material having a ferroelectric characteristic of being polarized only vertically; a source electrode and a drain electrode each in contact with the first polarization layer and spaced apart from each other; and a gate electrode disposed on the second polarization layer.