Atomic Segregation In Co-deposited Si-Al Coatings

Metamaterials recently attracted a wide interest in many areas of scientific research. Particularly, application of metamaterials is very promising in vacuum electronics devices of mm and sub-THz range. Dielectric substrate with metamaterials coating was used in several devices such as travelling wave tubes and backward wave oscillators. Use of metamaterials can be quite attractive if electrical properties of those can be controlled, for example, through the variation of basic materials properties. Here Si-A1 alloy is suggested as the base material for metamaterial formation. Two source magnetron co-sputtering deposition of Si-A1 alloys was utilized to obtain series of coatings with different chemical composition and thus different resistivity. Control of composition was provided by varying the power of Al magnetron source while power of Si source was constant. Three series of samples were deposited at different substrate temperatures. A sharp decrease in surface resistivity is observed while the Al content in the film changes smoothly. This result is explained by the segregation of Si and Al atoms due to Al diffusion during film deposition process.