Synthesis of the infrared transparent and conductive DLC coating based on PLD

Abstract

The diamond-like carbon (DLC) layer was deposited via pulsed laser deposition (PLD) to serve as an infrared anti-reflective and protective coating for the Si substrate, leveraging its low infrared absorption and high hardness. Concurrently, the Cu electrodes were grown with mask based on its excellent conductive property. A buffer-structure of SiC / gradient Ti-Cu-Ti layer / SiC layer was designed and prepared to address the severe mismatch interface between the Cu layer and Si substrate (or DLC layer), enhancing the adhesive strength of the transparent and conductive coating. The DLC coating with Cu skeleton exhibited an average transmission of 75.2 % in the wavelength range of 3–5 μm and a square resistance of 2.7 Ω/sq, showing a relatively high figure of merit. And this coating beard the vertical force of 2.74 N/cm from the scotch tape according to National Military Standard of ‘General Specifications for Optical films (GJB 2485–95)’. This work prioritized simultaneous MIR infrared transparency and conductivity along with protective function, whereas conventional materials like ITO and Ag grid optimized visible/near-IR performance or flexibility, therefore, a direct comparison with them was challenging due to the divergent design priorities.