The Effect of Ejection Angle in Ion-Beam Sputter Deposition of Superconducting Amorphous Beryllium Film

Ion-beam sputter-deposited amorphous Be films on silica substrates at different ejection angles are characterized by their superconducting properties. It is shown that the superconducting transition temperature of the film is varied by changing the ejection angle of the sputtered particles. To explain this, the role of incorporated oxygen and the contribution of highly energetic particles to the amorphous Be formation are discussed, taking account of both the anisotropic ejection of the direct recoiled target atoms measured by time-of-flight and the result of a Monte Carlo simulation of Be sputtering. The Monte Carlo simulation describes the angular distribution of the sputtered atoms with considerable success and is particularly helpful in revealing the contribution of energetic sputtered atoms of higher than 100 eV at low ejection angles.