The Design and Fabrication of a Pt/Ge/Pt/HfO₂ Multilayer for High-Temperature Infrared Selective Radiation

The spectrally selective films enhance infrared emissivity in the nondetection region to address the heat dissipation limitation of wide-band low-emissivity films, thereby more effectively suppressing infrared radiation caused by high-temperature surfaces. However, most designs of spectrally selective films are based on a metal/semiconductor multilayer structure, which is susceptible to elemental diffusion caused by a metal-induced crystallization (MIC) mechanism at high temperatures, resulting in a loss of spectral selectivity. Here, we propose a thermally stable multilayer Pt/Ge/Pt/HfO₂ film with spectral selectivity through thermal activation effect to form a crystalline Ge layer. This improved Pt/Ge/Pt/HfO₂ (I-PGPH), which acquires a more stable Ge layer, could inhibit the interdiffusion between the Pt and Ge films from the MIC process at high temperatures and achieves superior thermal stability. Compared with normal Pt/Ge/Pt/HfO₂ (PGPH), the I-PGPH increases the operation temperature from 400 to 600 °C and features excellent spectral selectivity at 600 °C, with a low emissivity of 0.18/0.39 in 3-5/8-14 μm bands and a high emissivity of 0.75 in the 5-8 μm range. This work demonstrates a method for enhancing spectral thermal stability of spectrally selective films, which provides considerable potential for advancing high-temperature engineered applications.