Real-time studies of thin film growth: Measurement and analysis of X-ray growth oscillations beyond the anti-Bragg point

摘要

Monitoring X-ray growth oscillations, i.e. temporal oscillations of the X-ray reflectivity during thin film growth, is an important technique for in-situ and real-time characterization of heteroepitaxy. Here we demonstrate the simultaneous acquisition and analysis of not only one, but a set of growth oscillations in a wide range of the reciprocal space (q-space). Importantly, the combined information of these growth oscillations removes ambiguities inherent in the analysis of a single (anti-Bragg) oscillation. Wide q-range measurements also enlarge the accessible parameter range in film thickness and roughness, as measurements at optimized q-values exhibit a larger amplitude and lower damping during growth. As an example we analyze oscillations at q = 1/2, 2/3, 3/4..., q_(Bragg) during molecular beam deposition of the organic semiconductor diindenoperylene using kinematic scattering theory. From this we derive the growth mode and the surface roughening with film thickness.