Multiple Time Scales in Diffraction Measurements of Diffusive Surface Relaxation

TL;DR

This study uses real-time x-ray scattering to analyze surface relaxation in SrTiO3 growth, revealing multiple exponential relaxation processes driven by a single activation energy.

Contribution

It demonstrates the presence of multiple time scales in surface relaxation during thin film growth, linked to discrete surface features and a single activation energy.

Findings

Multiple exponential relaxation of diffracted intensity observed.

Surface feature spacing influences relaxation time scales.

Activation energy consistent across different relaxation processes.

Abstract

We grew SrTiO3 on SrTiO3 (001) by pulsed laser deposition, using x-ray scattering to monitor the growth in real time. The time-resolved small angle scattering exhibits a well-defined length scale associated with the spacing between unit cell high surface features. This length scale imposes a discrete spectrum of Fourier components and rate constants upon the diffusion equation solution, evident in multiple exponential relaxation of the "anti-Bragg" diffracted intensity. An Arrhenius analysis of measured rate constants confirms that they originate from a single activation energy.