Diamond/GaInSn composites

Diamond/GaInSn composites

The rapid advancement of high-power electronic devices, including artificial intelligence (AI) processors, power semiconductors, and photovoltaic systems, has led to an unprecedented increase in heat flux density. Efficient thermal management is therefore critical to ensure device reliability, performance stability, and lifespan. Among various thermal management strategies, thermal interface materials (TIMs) play a pivotal role by minimizing interfacial thermal resistance between heat-generating components and heat sinks. However, conventional TIMs, such as polymer-based composites, are fundamentally limited by their low intrinsic thermal conductivity and poor long-term stability under elevated temperatures and high heat loads.

Liquid metals, particularly eutectic gallium-based alloys such as Ga–In–Sn (GaInSn), have emerged as promising next-generation TIMs due to their high intrinsic thermal conductivity, excellent fluidity, and superior conformability to irregular surfaces. These characteristics enable intimate interfacial contact and significantly reduce contact thermal resistance. Nevertheless, the relatively moderate thermal conductivity of GaInSn (~10 W·m⁻¹·K⁻¹) remains insufficient for next-generation high-power applications. To overcome this limitation, the incorporation of high thermal conductivity fillers into liquid metal matrices has attracted increasing attention.

Diamond, with an ultrahigh thermal conductivity exceeding 1800 W·m⁻¹·K⁻¹, is considered an ideal candidate for enhancing heat transport in composite TIMs. Diamond/GaInSn composites combine the exceptional heat conduction capability of diamond with the excellent wettability and compliance of liquid metals, offering a promising pathway toward high-performance thermal interface materials. However, the overall thermal performance of such composites is not solely determined by the intrinsic properties of the constituents, but is critically governed by the efficiency of heat transfer across the diamond–liquid metal interface.

A major challenge arises from the inherently weak interaction between diamond and liquid metals. The chemically inert surface of diamond leads to poor wettability and weak interfacial bonding, typically dominated by van der Waals interactions. This results in significant interfacial thermal resistance due to inefficient electron–phonon coupling and the presence of interfacial voids or gaps. Consequently, the expected enhancement in thermal conductivity is often far below theoretical predictions. Therefore, engineering the diamond–matrix interface to improve interfacial contact, bonding strength, and vibrational coupling has become a central issue in the development of high-performance diamond/liquid-metal composites.

Recent studies have demonstrated that surface modification of diamond is an effective strategy to address these challenges. Micro- and nanoscale surface structuring, achieved through methods such as oxidative etching or catalytic roughening, can significantly increase the effective contact area, reduce interfacial voids, and promote mechanical interlocking with the liquid metal matrix. In parallel, chemical modification approaches, including surface metallization, carbide interlayer formation, and functionalization, can enhance interfacial bonding by facilitating charge transfer and orbital hybridization, thereby improving electron–phonon coupling across the interface. Despite these advances, achieving a balance between interfacial bonding strength, structural integrity, and scalable processing remains a key challenge.