Perovskite Capacitor Stack With Dual Dielectrics and Low Lattice Mismatch
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Solution Overview
Problem
The challenge lies in developing capacitors with high dielectric constants and low leakage current densities, where the dielectric constant and leakage current are in a trade-off relationship, and the crystallinity of the capacitor is degraded due to lattice mismatch between electrodes and dielectric layers.
Innovation Solution
The solution involves a capacitor structure with a perovskite lower and upper electrode, a first dielectric layer with a high dielectric constant, and a second dielectric layer with a higher bandgap energy, both having a lattice mismatch of 5% or less, which are stacked to maintain crystallinity and reduce leakage current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dielectric layer with high dielectric constant is used, then capacitance increases, but leakage current increases
Solution Approach 1:
The dielectric layer is segmented into multiple sub-layers with different materials and properties. Specifically, a first dielectric layer (e.g., SrTiO3, BaTiO3, or (Ba, Sr)TiO3) is combined with a second dielectric layer (e.g., SrZrO3 or SrHfO3), where each layer contributes different characteristics to achieve both high capacitance and low leakage current.
Solution Approach 2:
The patent employs composite dielectric structures combining different oxide materials. The first dielectric layer uses perovskite-based materials with high dielectric constants, while the second dielectric layer uses materials with higher bandgap energies, creating a composite structure that leverages the advantages of both material types to simultaneously achieve high capacitance and low leakage.
2Object-generated harmful factors
If different dielectric layers are stacked to balance dielectric constant and bandgap energy, then leakage current decreases, but dielectric constant decreases
Solution Approach 1:
Different regions of the dielectric structure are assigned different local qualities: the first dielectric layer is optimized for high dielectric constant to maximize capacitance, while the second dielectric layer is optimized for high bandgap energy to minimize leakage. This local optimization allows each layer to perform its specific function effectively.
Solution Approach 2:
The patent adjusts material composition parameters and layer thickness ratios to optimize performance. By controlling the thickness of each dielectric layer and adjusting the compositional parameters of the oxide materials, the structure achieves a balance where the overall dielectric constant remains sufficiently high while leakage current is suppressed through the high bandgap layer.
3Reliability
If perovskite electrodes are used, then work function increases, but lattice mismatch degrades crystallinity
Solution Approach 1:
The patent modifies the compositional parameters of the perovskite electrode materials (such as SrRuO3, SrMoO3, SrIrO3, SrVO3, SrNbO3, or SrCoO3) and adjusts their thickness and structural parameters to reduce lattice mismatch with the dielectric layers. This parameter optimization maintains the high work function necessary for low leakage while minimizing crystallinity degradation.
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 configuration effectively suppresses the decrease in dielectric constant while achieving a low leakage current density, improving the charging capacity and stability of the capacitor.
Implementation Method 1
a second dielectric layer, having a band gap energy greater than that of the first dielectric layer, between the first dielectric layer and the upper electrode
Data Source
AI summary
A capacitor includes a lower electrode, a first dielectric layer provided on the lower electrode including a perovskite structure, an upper electrode including a perovskite structure, a first dielectric layer between provided on the lower electrode and the upper electrode; and a second dielectric layer, having a band gap energy greater than that of the first dielectric layer, provided between on the first dielectric layer and the upper electrode, the capacitor may have a low leakage current density and stable crystallinity, thereby suppressing a decrease in a dielectric constant.