Seed-free deposition of large-area adhesive diamond films on copper surfaces processed and patterned by femtosecond lasers

We demonstrate that femtosecond (fs) laser patterning of Cu can be exploited to realize seed-free deposition of large-area adhesive diamond films on Cu. Fs-laser-induced nanostructures promote diamond nucleation density and result in diamond film formation within a laser fluence window from 2.6 to 3.6 J cm^− 2. Diamond films deposited on Cu surfaces prepared outside this window experience either complete film detachment or formation of low-quality ball-like diamond grains. Diamond/substrate interface roughness plays a critical role in controlling diamond quality and adhesion between substrates and diamond films. Large-area adhesive diamond films have been achieved on Cu substrate surfaces that were first modified with fs-laser irradiation and then scribed into grid patterns. The scribed channels function as expansion joints for stress relief. Strain-free diamond films have been achieved by optimizing the grid size. Using fs-laser processing for seed-free deposition of large-area diamond films on Cu is of great significance for diverse applications, such as thermal management and power electronic devices.