Study of the dependence of deposition rate on the microwave attenuation behavior of ultra-thin Cu films

Full text: The production and use of lightweight, flexible and thin materials have been increasingly studied in the radar absorbing materials (RAM) area. Considering that this class of materials finds applications in the civilian sector in electronic device, in order to solve problems of EMI and EMC, for example, and also in the military one to reduce the radar cross section (eco-radar) of targets. Previous studies show that ultra-thin films of certain metals may exhibit absorption properties of the electromagnetic wave. This phenomenon is attributed to the transitive behavior that some materials present in nanometric scale (ASTM, 2006). The wave absorbing property by thin films depend on their crystallographic structure and experimental results show that amorphous films tend to have a better attenuation behavior of the electromagnetic wave, favored by the losses in the film material (Antonets, Kotov, Nekipelov, & Karpushov, 2004). In this work, ultra-thin Cu films were deposited (10-100 nm) on polymeric substrate based on polyethylene terephthalate (PET) by magnetron sputtering technique. Their electromagnetic properties were studied by scattering parameters (S-parameters) measurements using the reflection-transmission technique. A waveguide in the X-band (8.2 to 12.4 GHz) was used. The morphology of these films was evaluated by scanning electron microscopy and the structural ordering by small angle X-ray diffraction techniques. The correlation of results show that the microwave attenuating results present dependence on both film thickness and deposition rate used. Reference: [1]Antonets, I. V., Kotov, L. N., Nekipelov, S. V., & Karpushov, E. N. (2004). Conducting and reflecting properties of thin metal films. Technical Physics, 49 (11), 1496-1500. doi:10.1134/1.1826197 ASTM. E 2456-06 (2006). West Conshocken. (author)