Observed Effects of a Changing Step-Edge Density on Thin-Film Growth Dynamics

TL;DR

This study investigates how variations in step-edge density influence thin-film growth dynamics, revealing a fast smoothing mechanism that affects x-ray diffraction signals during SrTiO3 deposition.

Contribution

It demonstrates experimentally that surface step-edge density impacts growth smoothing, challenging existing kinematic theory predictions.

Findings

Observed x-ray intensity drops depend on growth phase.

Identified a fast smoothing mechanism linked to step-edge density.

Results suggest modifications to theoretical models of thin-film growth.

Abstract

We grew SrTiO3 on SrTiO3 [001] by pulsed laser deposition, while observing x-ray diffraction at the (0 0 .5) position. The drop dI in the x-ray intensity following a laser pulse contains information about plume-surface interactions. Kinematic theory predicts dI/I = -4sigma(1-sigma), so that dI/I depends only on the amount of deposited material sigma. In contrast, we observed experimentally that |dI/I| < 4sigma(1-sigma), and that dI/I depends on the phase of x-ray growth oscillations. The combined results suggest a fast smoothing mechanism that depends on surface step-edge density.