A-Axis Sapphire Wafers
UniversityWafer supplies A-axis sapphire wafers, also known as A-plane sapphire substrates, for thin-film, optical, electronic, and materials-science research. A-plane sapphire has a surface orientation of (11-20), providing a crystallographic surface that differs from commonly used C-plane (0001) sapphire.
Sapphire is single-crystal aluminum oxide (Al2O3) with high hardness, electrical resistivity, chemical stability, and thermal stability. Sapphire is also optically transparent over a broad spectral range, making it useful for both substrate and optical applications.
Why Use A-Plane Sapphire?
Crystal orientation determines the atomic arrangement exposed at the sapphire surface. Because sapphire is anisotropic, changing the wafer orientation can influence orientation-dependent optical and physical behavior as well as interactions between the substrate and deposited thin films.
A-plane sapphire can therefore be useful in experiments investigating orientation-dependent thin-film growth, surface properties, optical behavior, and crystallographic relationships between a substrate and deposited material. The suitability of A-plane sapphire for a particular film depends on the material system and deposition process.
Common A-Plane Sapphire Research Applications
- Thin-film deposition research
- Orientation-dependent materials studies
- Optical and photonic research
- Dielectric and electrically insulating substrates
- Surface-science experiments
- Crystallographic studies
- High-temperature materials research
Surface Finish and Wafer Specifications
Surface preparation can be important when sapphire is used as a research substrate. Depending on the application, researchers may require single-side polished (SSP) or double-side polished (DSP) wafers, along with controlled thickness, crystallographic orientation, surface quality, and other specifications.
When requesting a quote, include the desired wafer diameter, thickness, quantity, polishing requirements, orientation, and any other specifications required by your process.
Researchers comparing sapphire orientations can also review our C-plane sapphire wafers and our broader selection of sapphire wafers and substrates.
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What is A-Axis Sapphire?
A-axis sapphire, commonly referred to as A-plane sapphire, is single-crystal aluminum oxide (Al2O3) cut so that the wafer surface corresponds to the (11-20) crystallographic plane. Sapphire has the corundum crystal structure and is commonly described using a hexagonal crystallographic coordinate system.
Sapphire is an anisotropic material, meaning that some of its physical and optical properties depend on crystallographic direction. For substrate applications, crystal orientation is important because different cuts expose different atomic arrangements at the wafer surface.
Why Does Sapphire Orientation Matter?
The crystallographic orientation of a sapphire substrate can influence its interaction with deposited materials. In thin-film and epitaxial research, substrate orientation can affect nucleation, preferred film orientation, interface structure, surface morphology, and the crystallographic relationship between the film and substrate.
A-plane sapphire has been investigated as a substrate for oriented and epitaxial thin films. The suitability of this orientation depends on the deposited material, lattice relationship, deposition technique, temperature, surface preparation, and other process conditions.
A-Plane Sapphire for Thin-Film Research
The (11-20) surface provides a different surface symmetry and atomic arrangement from C-plane sapphire. This makes A-plane sapphire useful for researchers studying orientation-dependent film growth and other crystallographic effects.
Published research has demonstrated epitaxial or highly oriented growth of materials such as indium tin oxide (ITO) and iridium on A-plane sapphire. Results depend strongly on the particular film material and deposition conditions, so substrate orientation should be selected for the specific material system being investigated.
A-Plane vs. C-Plane Sapphire
A-plane and C-plane sapphire expose different crystallographic surfaces. C-plane sapphire corresponds to the basal (0001) plane, while A-plane sapphire corresponds to the (11-20) plane.
These orientations should not be considered universally interchangeable. The appropriate orientation depends on the intended thin film, device, optical experiment, surface process, and desired crystallographic relationship.
Is Sapphire Birefringent?
Yes. Sapphire is a uniaxial birefringent crystal. Its refractive behavior depends on the polarization and propagation direction of light relative to the crystal's optical axis. Sapphire therefore has ordinary and extraordinary refractive indices.
Birefringence can be important when sapphire is used in polarization-sensitive optical systems, spectroscopy, optical windows, laser systems, and other precision optical applications. The refractive indices and resulting birefringence vary with wavelength.
Important Properties of Sapphire
- High hardness: Sapphire provides excellent resistance to scratching and mechanical wear.
- Electrical insulation: Sapphire has high electrical resistivity and can be used as an insulating substrate.
- Thermal stability: Sapphire maintains useful mechanical and chemical properties at elevated temperatures.
- Chemical resistance: Sapphire is resistant to many chemicals and harsh processing environments.
- Broad optical transmission: High-quality sapphire can transmit light over a broad spectral range extending from the ultraviolet through the visible and into the infrared.
- Crystallographic anisotropy: Some optical, thermal, and mechanical properties vary with crystal direction.
A-Plane Sapphire Research Applications
A-plane sapphire substrates can be considered for applications in which crystallographic orientation, surface quality, electrical insulation, optical properties, or high-temperature stability are important.
- Thin-film deposition research
- Epitaxial and oriented film studies
- Surface-science research
- Optical and photonic experiments
- Dielectric and insulating substrates
- Crystallographic studies
- High-temperature materials research
Selecting an A-Plane Sapphire Wafer
Researchers selecting A-plane sapphire should consider wafer diameter, thickness, surface finish, crystallographic orientation tolerance, surface quality, and whether single-side polished (SSP) or double-side polished (DSP) material is required.
The appropriate specifications depend on the application. Thin-film and epitaxial experiments may require carefully controlled orientation and surface preparation, while optical applications may place additional emphasis on polishing quality, thickness, parallelism, and optical performance.