Potassium Sodium Niobate Thin Film Leakage Current Control
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Solution Overview
Problem
Conventional potassium sodium niobate thin films exhibit poor leakage current characteristics when subjected to high electric fields, with leakage current increasing rapidly beyond 100 kV/cm, and fail to achieve excellent ferroelectric and piezoelectric properties simultaneously.
Innovation Solution
A piezoelectric thin film element with a potassium sodium niobate thin film composition represented by the general formula (1−n)(K1-xNax)NbyO3-nM1M2O3, where M1 is Ca, Sr, or Ba, and M2 is Zr, Sn, or Hf, with specific ranges for x, y, and n (0.25≦x≦1.00, 0.85≦y≦1.10, and 0.01≦n≦0.10), which suppresses rapid leakage current increase and maintains excellent ferroelectric characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional potassium sodium niobate thin films are used, then piezoelectric characteristics can be achieved, but leakage current increases rapidly when electric field exceeds 100 kV/cm
Solution Approach 1:
The patent changes the compositional parameters of the potassium sodium niobate thin film by incorporating solid solutions of M1M2O3 (where M1 is Ca, Sr, or Ba and M2 is Zr, Sn, or Hf) with specific mole ratios (0.01≦n≦0.10). This compositional parameter change suppresses the rapid increase in leakage current at high electric fields while maintaining excellent piezoelectric characteristics, resolving the contradiction between reliability and harmful factors.
Solution Approach 2:
The patent creates a composite material system by combining potassium sodium niobate (KNN) with solid solutions of M1M2O3. This composite structure leverages the beneficial properties of both materials: KNN provides excellent piezoelectric characteristics while the M1M2O3 solid solution component suppresses leakage current at high electric fields, thereby resolving the technical contradiction.
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
The solution achieves a piezoelectric constant d33* comparable to or exceeding that of potassium sodium niobate thin films without solid solutions, while maintaining low leakage current and high ferroelectric characteristics, even at high electric fields.
Implementation Method 1
Piezoelectric bodies are now widely used as materials for functional electronic components such as actuators and sensors
Implementation Method 2
perovskite-type ferroelectric materials are mainly used which are represented by the general formula Pb(Zr,Ti)O3 referred to as PZT
Data Source
AI summary
A piezoelectric thin film element that includes a substrate, a lower electrode on the substrate, a piezoelectric film on the lower electrode, and an upper electrode on the piezoelectric film. The piezoelectric film is a potassium sodium niobate film represented, as its main constituent, by the general formula (1−n)(K1-xNax)NbyO3-nM1M2O3 in which M1 is any one of Ca, Sr, and Ba, and M2 is Zr, and x, y, and n respectively are within the ranges of: 0.25≦x≦1.00; 0.85≦y≦1.10; and 0.01≦n≦0.10. Alternatively, M2 is any one of Sn and Hf, and x, y, and n respectively are within the ranges of: 0.25≦x≦1.00; 0.90≦y≦1.05; and 0.01≦n≦0.10.