Mechanical properties of a-Si:H films studied by Brillouin scattering and nanoindenter

Abstract

A series of a‐Si:H films has been prepared by rf sputtering in a H₂‐Ar gas mixture. To obtain films with different hydrogen content the hydrogen portion of the gas mixture was changed from 0% to 20%. The shear modulus μ was then measured by the frequency of the surface phonon (Rayleigh wave). The stiffness S and the ultramicrohardness H were measured by using a nanoindenter. From the shear modulus μ and the stiffness S, the Young’s modulus E and Poisson’s ratio ν were calculated. The intrinsic mechanical stress was measured by the bending‐beam method. With increasing hydrogen content of the films, the decrease of Young’s modulus, microhardness, and internal stress are observed.