Laser Heating in Diamonds Amplifies under Low-Substrate Conductivity and Polymer Layers (0.2–0.35 W/m·K)

Diamonds, prized for their exceptional thermal conductivity, surprisingly experience significant heating under laser illumination when placed on certain materials, a phenomenon Md Shakhawath Hossain, Jiatong Xu, and Thi Ngoc Anh Mai, along with their colleagues, now investigate in detail. This research demonstrates that the thermal conductivity of the supporting substrate and the presence of even ultra-thin polymer layers between the diamond and substrate dramatically influence localised heating, an effect previously underestimated in these materials. The team’s findings reveal substantial heating occurs even at low laser powers when diamonds rest on substrates with poor thermal conductivity, and that a polymer layer just a few micrometres thick markedly amplifies this effect. By combining precise experiments with detailed computer simulations, the researchers provide crucial insights for optimising sample preparation and selecting appropriate substrates for sensitive applications such as nanoscale thermometry and quantum sensing.

Raman Spectra Confirm SiV Diamond Quality

Supporting experiments and simulations detail laser-induced heating in silicon-vacancy diamonds, focusing on how substrate materials and interfacial layers affect temperature rise. Detailed analysis confirms the high crystalline quality of the diamonds and the absence of defects that could compromise temperature measurements. Photoluminescence measurements at varying temperatures establish a calibration curve relating spectral shifts to absolute temperature, allowing for precise temperature readings. Analysis of polymer film thickness provides crucial information for modeling heat transfer. Measurements reveal how polymer layer thickness affects temperature rise, acting as a thermal resistance that controls heat dissipation. Time-resolved measurements demonstrate the stability of the silicon-vacancy center under continuous laser excitation. Computational models simulate heat transfer within the diamond and substrate, validating experimental findings.

Thermal Calibration of Silicon-Vacancy Diamonds on Substrates

Scientists investigated laser-induced heating in silicon-vacancy diamonds on substrates with varying thermal conductivities and interfacial polymer thicknesses. The study employed diamonds synthesized via a high-pressure, high-temperature method and calibrated them against a bulk diamond substrate to minimize thermal effects. Annealing at 200°C enhanced particle-substrate adhesion and ensured high-quality crystalline carbon. Measurements revealed substantial heating even at low excitation power when using amorphous holey carbon, while noticeable heating in glass and polydimethylsiloxane required higher powers.

A polymer layer as thin as 2. 2μm induced significant heating, demonstrating the strong influence of both substrate and polymer thickness on the local thermal response. To validate these findings, scientists developed a steady-state 3D heat transfer model using COMSOL Multiphysics software, simulating the spatial temperature distribution. This computational approach corroborated the experimental results, establishing design principles for minimizing thermal artifacts in diamond-based nanoscale thermometry and quantum devices. The work provides practical guidance for substrate selection and sample preparation, enabling optimization of conditions for accurate temperature measurements.

Laser Heating Scales with Substrate Conductivity

Scientists conducted a systematic investigation of laser-induced heating in silicon-vacancy diamonds, revealing the significant influence of both substrate thermal conductivity and interfacial polymer layers. Experiments demonstrate that even at low excitation power, thin amorphous holey carbon exhibits substantial heating. In contrast, glass and polydimethylsiloxane show noticeable heating only when the excitation power exceeds a certain threshold. These results establish a direct correlation between substrate thermal conductivity and the magnitude of laser-induced heating. Further analysis focused on the impact of interfacial polymer layers, revealing that a thickness of just 2.

2μm induces significant heating, highlighting the critical role of even extremely thin polymer residues in amplifying local heating effects. The team validated these experimental findings using COMSOL Multiphysics simulations, confirming the accuracy of the observed thermal responses. These measurements provide crucial guidance for optimizing substrate selection and sample preparation in nanoscale thermometry and quantum sensing applications. The work establishes that minimizing both low thermal conductivity substrates and interfacial polymer layers is essential for reducing thermal artifacts and achieving reliable temperature measurements with diamond-based sensors.

Substrate Conductivity Amplifies Microdiamond Laser Heating

This research systematically investigates laser-induced heating in microdiamonds placed on substrates with varying thermal conductivities and interfacial polymer layer thicknesses. Results demonstrate a strong correlation between substrate thermal conductivity and the magnitude of laser heating; diamonds on substrates with lower thermal conductivity exhibit significant heating at substantially lower laser power. Specifically, substantial heating was observed in diamonds on thin amorphous holey carbon even with only 500 microwatts of power, while bulk diamond and silicon required much higher power. The study further reveals that even a thin, 2.

2-micrometer polymer layer between the diamond and the substrate significantly amplifies laser-induced heating at laser powers of 2 milliwatts and above. These findings are supported by detailed three-dimensional heat transfer simulations, validating the experimental observations and providing a robust understanding of the underlying thermal processes. These findings provide practical guidance for selecting appropriate substrates and optimizing sample preparation techniques for applications in thermometry, photonics, quantum technologies, and sensing. Careful consideration of substrate thermal conductivity and interfacial layer thickness is crucial for minimizing unwanted heating effects and ensuring the reliability of diamond-based devices.