Distinctive millimeter-wave band electromagnetic properties of µm-thick Al-Si films upon dielectric substrates

Results of experimental study of the reflection and transmission losses in the V-band of µm-thick Si-Al films on the dielectric substrates are considered. Two sources magnetron co-sputtering deposition of Si-Al alloys was utilized to prepare a series of coatings of varied chemical composition and thus different properties. Control over films composition was provided by variation of Al magnetron power source with constant Si magnetron power source. Segregation of Si and Al atoms in Al-Si films was observed at a specific power of Al magnetron source during the deposition: Si atoms were mainly concentrated at the lower levels of the film adjacent to the substrate, while Al atoms tended to concentrate near the upper surface of the coating. Distinct electromagnetic properties of Al-Si films fabricated at the transient phase of segregation mode were observed: one side of the film demonstrated low reflection in the millimeter-band while almost full reflection was observed from the other side. Such properties of µm-thick Si-Al films upon dielectric substrates can be useful for development of millimeter-wave antenna modules technology.