Determination of Vickers microhardness in β-Ga2O3 single crystals grown from their own melt
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-05-15 |
| Journal | Scientific and technical journal of information technologies mechanics and optics |
| Authors | L.I. Guzilova, V.N. Maslov, Katerina E. Aifantis, А. Е. Романов, V.I. Nikolaev |
| Institutions | Ioffe Institute, ITMO University |
| Citations | 1 |
| Analysis | Full AI Review Included |
6CCVD Technical Analysis & Market Opportunity: Vickers Microhardness in $\beta$-Ga2O3 Single Crystals
Section titled “6CCVD Technical Analysis & Market Opportunity: Vickers Microhardness in $\beta$-Ga2O3 Single Crystals”Executive Summary
Section titled “Executive Summary”This document analyzes a study detailing the mechanical properties of $\beta$-Ga2O3$ single crystals, a critical wide-bandgap (WBG) material for next-generation power electronics and UV optoelectronics. The results are vital for optimizing substrate preparation, a demanding application perfectly suited for 6CCVD’s ultra-hard MPCVD diamond solutions.
- Core Achievement: Determination of the average Vickers Microhardness ($H_v$) for $\beta$-Ga2O3 single crystals on the (001) crystallographic face.
- Key Value Proposition: The average $H_v$ was found to be 8.91 GPa within the 0.3 N to 1.0 N load range.
- Material Comparison: $\beta$-Ga2O3$ is mechanically softer than GaN (12.0-14.4 GPa) but harder than GaP (7.75-8.48 GPa).
- Engineering Implication: The data is essential for developing machining and polishing processes required for fabricating high-quality $\beta$-Ga2O3 substrates and devices.
- Abrasive Recommendation: The research explicitly recommends abrasives with hardness greater than 8.91 GPa, such as Silicon Carbide (SiC, 27.4-34.3 GPa) and electrocorundum (Al2O3, 17.6-23.5 GPa).
- 6CCVD Advantage: MPCVD diamond (up to 98 GPa) provides the highest achievable hardness, guaranteeing superior wear resistance and allowing for atomic-level precision necessary for advanced WBG substrate finishing.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Material Analyzed | $\beta$-Ga2O3$ Single Crystal | N/A | Grown from melt via free crystallization | | ||
| | Crystallographic Face Tested | (001) | N/A | Cleavage plane (used for substrate applications) | | |||
| | Average Vickers Hardness ($H_v$) | 8.91 | GPa | Measured across 0.3 N - 1.0 N load range | | |||
| | Maximum Measured $H_v$ ($\beta$-Ga2O3$) | 9.351 | GPa | Measured at 0.7 N load | | |||
| | Minimum Measured $H_v$ ($\beta$-Ga2O3$) | 8.356 | GPa | Measured at 0.3 N load | | |||
| | Comparison Material $H_v$ (GaN) | 12.0 - 14.4 | GPa | Epitaxial layer on 6H-SiC (0001) substrate | | |||
| | Comparison Material $H_v$ (GaP) | 7.75 - 8.48 | GPa | Epitaxial layer on GaP:S (111) substrate | | |||
| | Recommended Abrasive (SiC) $H_v$ | 27.4 - 34.3 | GPa | Used for mechanical processing of WBG materials | | |||
| | Indenter Type | Diamond Pyramid | N/A | Four-sided, Vickers method | |
Key Methodologies
Section titled “Key Methodologies”The study focused on obtaining precise and reliable microhardness values necessary for mechanical processing development.
- Crystal Growth: $\beta$-Ga2O3$ single crystals were grown using the free crystallization method (growth from their own melt) utilizing the specialized “Garnet-2M” equipment.
- Sample Preparation: The crystals were analyzed on the (001) crystallographic face, which corresponds to the cleavage plane.
- Surface Quality Analysis: The surface quality of the (001) cleavage plane was confirmed using Atomic Force Microscopy (AFM), showing regions that were atomically smooth.
- Microhardness Testing: Hardness measurements were performed using the Vickers method via a PMT-3 microhardness tester.
- Indentation Parameters:
- Indenter: Four-sided diamond pyramid (Vickers geometry).
- Load Range (P): Varied from 0.2 N up to 1.0 N (specific data reported for 0.2, 0.3, 0.5, 0.7, 0.8, and 1.0 N).
- Hardness Calculation: $H_v$ was calculated using the applied load (P) and the square of the diagonal (d) of the resulting indentation mark, related by the formula $H_v = (1.854 \times P) / d^{2}$.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The requirement for machining WBG semiconductors like $\beta$-Ga2O3$ (8.91 GPa) and GaN (up to 14.4 GPa) mandates the use of materials significantly harder than the target substrate. 6CCVD specializes in the highest purity, hardest material available: MPCVD synthetic diamond ($H_v \approx 98$ GPa).
Applicable Materials for WBG Substrate Processing
Section titled “Applicable Materials for WBG Substrate Processing”6CCVD provides the optimal diamond material solutions for the precision machining and polishing of $\beta$-Ga2O3$, GaN, and SiC substrates, far exceeding the performance of SiC and electrocorundum abrasives cited in the paper.
| 6CCVD Material | Application Focus | Relevant Capability | | :--- | :--- | :--- | | Optical Grade SCD | Ultra-precision tool inserts, AFM/micro-indentation tips, single-point diamond turning (SPDT) tools. | Highest purity (low defect density), necessary for achieving the Ra < 1nm finishes required on WBG substrates. | | High-Purity PCD | Large-area polishing plates, grinding wheels, chemical mechanical polishing (CMP) conditioning plates. | Available in large formats (up to 125mm wafers) for scalable production processes; customizable thickness up to 500 µm. | | Thermal Grade SCD | Heat spreaders for Ga2O3/GaN power devices. | Diamond offers superior thermal conductivity (up to 2000 W/mK) crucial for managing heat generated by WBG devices operating at high temperatures and fields. |
Customization Potential
Section titled “Customization Potential”High-value WBG research and commercial production demand materials tailored precisely to the processing tool chain. 6CCVD offers end-to-end customization capabilities to meet these specific needs:
- Custom Dimensions and Shaping: We provide custom laser cutting and shaping of both SCD and PCD plates up to 125mm diameter to fit proprietary tooling geometry.
- Ultra-Low Surface Roughness: Our advanced polishing techniques achieve industry-leading surface quality, guaranteeing Ra < 1 nm for SCD and Ra < 5 nm for Inch-size PCD, essential for minimizing subsurface damage during Ga2O3 substrate preparation.
- Integrated Metalization: If $\beta$-Ga2O3$ devices require integrated heat spreading or electrical contacts, 6CCVD offers in-house metalization services, including Ti, W, Au, Pt, Pd, and Cu layers, ensuring robust adhesion and reliable interfaces.
Engineering Support
Section titled “Engineering Support”The success of WBG semiconductor fabrication hinges on precise material selection and process optimization. 6CCVD’s in-house PhD-level engineering team specializes in the mechanical and thermal management of advanced materials. We routinely assist clients working on similar Wide Bandgap Semiconductor Substrate Preparation and High-Frequency Power Electronics projects, ensuring the appropriate diamond grade and geometry are chosen for optimal yield and performance.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).
View Original Abstract
The results of microhardness measurements of β-Ga2O3 single crystals for (001) crystallographic face are reported. The crystals were grown by the free crystallization with the “Garnet-2M” equipment. Microhardness values were determined by the Vickers method at varying loads. A four-sided diamond pyramid was used as an indenter. The average value of gallium oxide microhardness was equal to 8.91 GPa. We have carried out comparison of the values obtained with the microhardness for the other wide bandgap semiconductors - epitaxial GaN layers grown on 6H-SiC and GaP layers grown on GaP:S. The findings are usable for machining process development of β-Ga2O3 single crystal substrates. In particular, silicon carbide and electrocorundum may be recommended for β-Ga2O3 machine processing.