The effect of the deposition rate on morphology, opto-electronic properties and formation intermetallic compounds of Au–Sn alloys

Abstract

Microstructure and opto-electronic properties of thin films strongly depend on the deposition conditions. The 50 nm gold-tin alloy (Au-50%at.Sn and Au-67%at.Sn) layers were prepared using the physical vapour deposition technique. The tin and gold layers were deposited on the SiO2 - coated Si substrates in two systems Au∖Sn and Sn∖Au at four different deposition rates in the range from 0.05 Å/s up to 2.50 Å/s. The influence of the deposition rate on the sample morphology was investigated using atomic force microscope and X-ray diffraction. Changes in the microstructure of the Au–Sn layers cause variations in their opto-electronic properties. These features were examined using spectroscopic ellipsometry measurements. We found that Au-50%at.Sn alloy layers exhibit significantly lower values of optical resistivity than those obtained for Au-67%at.Sn alloy films, whereas the lowest value (29 μΩcm) was obtained for Au-50%at.Sn deposited at 0.15 Å/s and 0.50 Å/s.