Breakthrough in Diamond-Based Gallium Oxide Heterogeneous Integration Achieved by CAS Research Teams

The Chinese Academy of Sciences (CAS) announced a major breakthrough in diamond-based gallium oxide (Ga₂O₃) heterogeneous integration materials and devices. This progress was achieved through the collaboration of the XOI Heterogeneous Integration Team from the Shanghai Institute of Microsystem and Information Technology (SIMIT) and the Ultra-Wide Bandgap Semiconductor Research Team at the Nanjing Electronic Devices Institute.

Innovation in XOI Wafer Transfer Technology

The SIMIT research team developed an innovative XOI wafer transfer technique, becoming the first to successfully integrate an arrayed gallium oxide single-crystal thin film with a 1-inch diamond substrate.

Key performance milestones include:

• Material quality: Post-transfer gallium oxide single-crystal thin films achieved a rocking curve full width at half maximum (FWHM) of 78 arcsec and a surface roughness of just 0.35 nm.
• Interface quality: The diamond/gallium oxide interface transition layer thickness was less than 2 nm, with a record-low thermal resistance of 21.7 m²·K/GW, the best-reported value to date.

Superior RF Device Performance and Thermal Management

The integration significantly enhanced the radio frequency (RF) device performance and heat dissipation capabilities:

• Device Performance: The fabricated RF device demonstrated a saturation current as high as 810 mA/mm. The maximum oscillation frequency before de-embedding reached 61 GHz, the highest value reported so far.
• Thermal Management: Under equivalent power conditions, the peak junction temperature of the device was reduced by 250°C compared to gallium oxide homogenous devices, achieving an 11-fold improvement in heat dissipation.
• Thermal Resistance: The device thermal resistance measured only 5.52 W·mm/K, greatly enhancing operational stability and longevity.

This innovation proves that diamond-based gallium oxide heterogeneous integration can significantly boost device performance and thermal management, addressing critical challenges in RF and power electronics applications.

Advantages of XOI Transfer Technology

The XOI wafer transfer technology offers several practical advantages:

• Low Cost: The method reduces manufacturing expenses.
• Surface Quality Tolerance: It is unaffected by the surface quality of the wafer.
• Broad Compatibility: The technique is compatible with heterogeneous integration of thin films of varying sizes, materials, and orientations onto diverse substrates.

Implications and Future Outlook

This breakthrough highlights the superior thermal management and RF capabilities of wafer-level diamond-based gallium oxide heterogeneous integration materials, positioning it as a pivotal development following silicon-based and silicon carbide-based gallium oxide heterointegration.

The successful integration of diamond substrates with gallium oxide opens up new frontiers for high-performance electronic devices, particularly in RF power devices and wide-bandgap semiconductors. This research not only advances gallium oxide technology but also establishes a new paradigm for heterogeneous material integration.