CVD Diamond Deposition Coating on Titanium Thermal Management

CVD Diamond Deposition Coating on Titanium 

At Diasemi, we focus on advancing next-generation thermal management materials for high-power photonics. Diamond, with its unmatched thermal conductivity, is a key enabler for dissipating heat in high-power laser systems such as Ti:sapphire amplifiers. However, conventional single-crystal diamond remains constrained by high cost and limited size. To overcome these barriers, Diasemi has developed scalable polycrystalline CVD diamond films tailored for optical and laser-grade applications.

A persistent challenge in integrating diamond with laser host crystals is the severe thermal expansion mismatch, which can compromise bonding quality, introduce stress, and reduce reliability under high optical loads. At Diasemi, we explore engineered metal interlayers to bridge these mismatches. This work demonstrates our optimized MPCVD diamond heat-sink film grown on Ti:sapphire, enabled by a chromium (Cr) adhesion and buffer interlayer.

Materials and Methods

Diasemi utilized laser-grade Ti:sapphire substrates as the base material. A Cr interlayer was deposited using high-uniformity magnetron sputtering optimized for thermal interface applications. The substrates then underwent our proprietary nanodiamond seeding process to ensure high nucleation density prior to MPCVD growth.

Diamond films were deposited in Diasemi’s production-calibrated MPCVD platforms, engineered for high-purity, low-stress optical diamond coatings. Post-deposition characterization included SEM, XRD, Raman spectroscopy, and thermal property evaluation. To further understand interfacial bonding at the atomic level, Diasemi applied DFT simulations to study Cr–C interactions and adhesion mechanisms.

Results and Discussion

Optical microscopy revealed that Diasemi’s Cr-coated Ti:sapphire substrates supported uniform, continuous diamond film formation, unlike uncoated samples. XRD confirmed the presence of Cr and carbide phases (Cr₃C₂), indicating strong interfacial reactions beneficial for adhesion.

Charge-density difference analysis and carbon adsorption energy calculations demonstrated strong chemical interaction between Cr and carbon—consistent with robust diamond nucleation and bonding. SEM revealed that the Cr interlayer modified grain orientation and enhanced film uniformity.

DFT results showed high binding energy between Cr (110) and diamond (110) planes, validating our interlayer design strategy. Raman spectroscopy confirmed high-quality diamond growth with controlled sp³/sp² content. Thermal diffusivity measurements revealed a significant enhancement once the diamond film was applied, showcasing superior heat-spreading capability.