Publication of a Research Paper on Large-Area (111) Diamond Substrate Fabrication Technology -Research achievements on diamond substrates for next-generation power semiconductors and quantum devices-
Orbray Co., Ltd. has published a research paper summarizing its achievements in large-area diamond substrates for semiconductor applications in the international journal Applied Physics Express.
The paper is entitled:
“Freestanding 30 mm square {111} twin-free heteroepitaxial diamonds grown on highly-misoriented {0001} sapphire substrates.”
In 2025 March, we announced the successful fabrication of a 20 mm square (111) diamond substrate—the largest size in the world—using heteroepitaxial growth on sapphire substrates. In this study, we have established a further technology for producing larger, 30 mm square, high-quality and high-purity freestanding (111) single-crystal diamond substrates. Additionally, we identified key growth conditions for suppressing twin defects, which are difficult to control during crystal growth.
These results are contributing to the advancement of material research for next-generation high-voltage power semiconductor devices and quantum devices such as quantum sensors.
URL: https://iopscience.iop.org/article/10.35848/1882-0786/ae4b05
DOI : 10.35848/1882-0786/ae4b05 | CC Creative Commons BY 4.0
Table of contents [close]
1. Summary of the Research Results
(1) Overview
In this study, diamond was grown using a microwave plasma CVD method on sapphire substrates with an iridium buffer layer.
By using sapphire substrates with a large misorientation in a specific direction, we successfully controlled the diamond crystal growth mode (step-flow growth). As a result, we succeeded in fabricating large-area (111) diamond substrates while suppressing twin formation.
As a result, we achieved a 30 mm square freestanding single-crystal (111) diamond substrate, whereas conventionally grown (111) diamond substrates were typically limited to sizes of only a few millimeters.
(2) Key Features of the Results
- Successful fabrication of a 30 mm square freestanding (111) single-crystal diamond substrate
- X-ray diffraction confirmation of a twin-free single-crystal structure across the entire substrate
- Discovery that a relatively large misorientation angle of the sapphire substrate promotes step-flow growth, and that a specific misorientation direction (〈11-20〉) is critical for suppressing twin formation
2. Background
Diamond has attracted significant attention as a next-generation power semiconductor material because of its exceptional properties, including:
- High breakdown voltage
- Extremely high thermal conductivity
- High carrier mobility
Diamond semiconductor research mainly utilizes two crystal orientations: (100) and (111).
(100) Diamond
It is relatively easy to fabricate and has already been used in industrial applications, particularly in power semiconductor device research.
(111) Diamond
It has advantages such as relatively easier control of n-type doping and the ability to align the spin orientation of NV centers used in quantum sensors.
For these reasons, (111) diamond is considered an important material for both power and quantum devices. However, it is challenging to suppress twin defect formation and to fabricate large-area substrates.
3. Publication Details
The results of this study have been published as follows:
Title:
Freestanding 30 mm square {111} twin-free heteroepitaxial diamonds grown on highly-misoriented {0001} sapphire substrates
Journal:
Applied Physics Express
Publication Date:
March 11, 2026
4. Future Outlook
The (111) diamond substrate fabrication technology developed in this study is expected to be applied to:
- Next-generation power semiconductor devices
- High-sensitivity quantum sensors
- Electronic devices for extreme environments
Going forward, we will continue research aimed at further increasing substrate size and quality, as well as developing doped substrates for device applications.
| 【Contact us regarding this press release】 Orbray Co., Ltd., Diamond Sales Division Substrate Sales Team TEL：+81-3-3919-0101 |
