β-Ga₂O₃ MOSFETs: Diamond TSL and Si Microchannel Heat Dissipation

agoa.top China

Overview

Researchers have developed a hybrid thermal management strategy combining a diamond thermal spreading layer (TSL) with substrate-embedded silicon microchannels to mitigate self-heating in β-Ga₂O₃ MOSFETs. This approach reduces peak device temperature by approximately 55.6 K, achieving performance within 5 K of high-cost diamond microchannel solutions.

In Depth

Key Findings

The proposed hybrid thermal management strategy significantly enhances heat dissipation in β-Ga₂O₃ MOSFETs by integrating a 5 μm thick diamond thermal spreading layer (TSL) with silicon-substrate-embedded microchannels. This configuration reduces the peak device temperature by approximately 55.6 K. When compared to state-of-the-art substrate-embedded diamond microchannel strategies, the performance gap is only 5 K, offering a more cost-effective and manufacturable alternative.

Technical Details

The research utilized a cross-platform electro-thermal coupling modeling method, extracting equivalent heat sources via Sentaurus TCAD simulations and performing 3D thermal simulations in COMSOL. The study identified that the primary thermal bottleneck in [010]-oriented β-Ga₂O₃ MOSFETs is suppressed lateral heat spreading due to low in-plane thermal conductivity.

• Heat Spreading: The diamond TSL increased the heat spreading angle from 32.2° to 88°, expanding the effective heat transfer area by approximately 80 times.
• Interfacial Resistance: Due to the efficiency of the lateral spreading, the effect of the diamond/substrate interfacial thermal resistance on junction temperature was found to be negligible.
• Optimization: The study systematically analyzed variables including TSL thickness, interfacial thermal resistance, microchannel position, flow velocity, and external thermal resistance.

Background & Context

β-Ga₂O₃ is a candidate for next-generation high-voltage power electronics due to its bandgap of approximately 4.8 eV and a critical breakdown field strength of up to 8 MV/cm. However, it suffers from low and anisotropic thermal conductivity (approximately 27.1 W m⁻¹ K⁻¹ along the [010] direction and 10.7 W m⁻¹ K⁻¹ along the [100] direction), which causes severe localized self-heating and limits device reliability.

Significance & Outlook

By overcoming the lateral heat dissipation bottleneck, this hybrid strategy balances high thermal performance with manufacturing feasibility. It provides a theoretical and engineering-valuable solution for the thermal design of high-power β-Ga₂O₃ devices, reducing the reliance on prohibitively expensive full-diamond microchannel substrates.

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