<title>Structural and optical properties of zinc selenide thin films deposited by rf magnetron sputtering</title>

Abstract

In this work, ZnSe thin films were deposited by radio frequency magnetron sputtering onto oriented silicon substrates. Three sets of samples were produced by varying the argon working gas pressure, and changing the sputtering power supply. The effect of the different growth conditions on the structural and optical properties of the ZnSe films was investigated by using XRD and FTIR spectroscopy. In particular, x-ray diffraction was used in order to study the residual strains and texture. The ZnSe coatings were grown in the cubic polymorph with the grains preferentially oriented for all the investigated pressures with the exception of 0.5 Pa. An in-plane residual stress reversal, which changed from compressive to tensile by going from the low to the high-pressure sample set, was observed. At the 0.5 Pa pressure, the ZnSe coatings were both in compressive and tensile state, according to the power supply value. These result have been correlated with the momentum of reflected neutral in order to find an exhaustive description of the deposition process. At low momentum values, the ZnSe films show tensile state, low refractive index, grains preferentially oriented, while at high momentum they were in compressive state, refractive index very alike to the bulk and grains randomly oriented.