Abstract
X-ray reflectivity was used to measure in situ the surface roughness and thickness of a thin film during thin-film growth. In this experiment, the sample and detector positions were held at fixed angles. An oscillating reflectivity intensity as a function of time was observed as the film thickness grew. The oscillation amplitude was damped as the surface roughness increased. Surface roughness as a function of time can be determined by analyzing the profile of oscillation intensity.