PdCoO2 Delafossite Thin Films for Heat-Resistant Schottky Electrodes
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Solution Overview
Problem
Conventional Schottky electrodes, such as those made of platinum, have insufficient heat resistance and reliability for high-power applications, while delafossite-type oxides like palladium cobalt oxide exhibit high electrical conductivity but face challenges in producing thin films with optimal crystal grain size, film thickness, and surface roughness for effective use in power devices.
Innovation Solution
A method involving target production, film deposition by sputtering, and annealing to produce palladium cobalt oxide thin films with crystal grains between 100 nm and 1000 nm, film thickness greater than critical thickness, and roughness less than 4 nm, using a single target to enhance electrical conductivity and suitability for Schottky electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delafossite-type oxide thin films are produced for Schottky electrodes, then electrical conductivity is improved, but manufacturing precision of crystal grain size and surface roughness deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing substrate temperature (623-773 K), oxygen partial pressure (1-100 mTorr), and deposition time to achieve the desired crystal grain size (100-1000 nm) and surface roughness (≤4 nm) while maintaining high electrical conductivity. This resolves the contradiction by finding the optimal parameter window that satisfies both conductivity and manufacturing precision requirements.
Solution Approach 2:
The patent employs periodic action through pulsed-laser deposition, where the laser irradiates the target in periodic pulses to deposit material layer by layer. This periodic deposition process enables precise control over crystal grain formation and surface morphology, achieving both high conductivity and manufacturing precision simultaneously.
2Ease of manufacture
If conventional Schottky electrodes are used, then manufacturing simplicity is maintained, but heat resistance and reliability deteriorate
Solution Approach 1:
The patent uses composite materials by combining delafossite-type oxide (PdCoO2) with gallium oxide substrate to create a Schottky electrode structure. This composite approach provides both high heat resistance from the oxide materials and improved electrical conductivity, while the sputtering deposition method maintains manufacturing simplicity through a single-step process.
3Reliability
If pulsed-laser deposition is used to produce PdCoO2 thin films, then electrical conductivity is improved, but device complexity increases
Solution Approach 1:
The patent replaces the complex pulsed-laser deposition system with a sputtering deposition system. This substitution simplifies the production apparatus and process while still achieving high electrical conductivity through controlled deposition parameters, thereby reducing device complexity without sacrificing performance.
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 produced thin films exhibit high electrical conductivity comparable to elemental metals, suitable for Schottky electrodes, with improved heat resistance and reliability, enabling large-area industrial production and compatibility with materials like gallium oxide.
Implementation Method 1
film deposition by sputtering
Implementation Method 2
annealing to produce palladium cobalt oxide thin films
Data Source
AI summary
A palladium cobalt oxide thin film, a delafossite-type oxide thin film, a Schottky electrode having a delafossite-type oxide thin film, a method for producing a palladium cobalt oxide thin film, and a method for producing a delafossite-type oxide thin film are provided. In the palladium cobalt oxide thin film, the crystal grain size in the film is 100 nm or more and 500 nm or less, the thickness is greater than the critical film thickness, and the roughness value in the thickness direction is 4 nm or less.