Epitaxial growth with pulsed deposition: Submonolayer scaling and Villain instability

TL;DR

This study models pulsed laser deposition (PLD) to understand its surface smoothing effects, finding limited improvement over molecular beam epitaxy (MBE) and suggesting other factors contribute to PLD's experimental surface quality.

Contribution

The paper introduces a simple model for PLD neglecting adatom mobility, analyzing its scaling properties and effects of Ehrlich-Schwoebel barriers to compare with MBE.

Findings

PLD can produce smoother surfaces than MBE in certain parameter ranges

The surface quality improvement in PLD is weak and limited to specific conditions

Deposition pulses alone do not fully explain the experimental smoothness of PLD-grown surfaces

Abstract

It has been observed experimentally that under certain conditions pulsed laser deposition (PLD) produces smoother surfaces than ordinary molecular beam epitaxy (MBE). So far the mechanism leading to the improved quality of surfaces in PLD is not yet fully understood. In the present work we investigate the physical properties of a simple model for PLD in which the transient mobility of adatoms and diffusion along edges is neglected. Analyzing the crossover from MBE to PLD, the scaling properties of the time-dependent nucleation density as well as the influence of Ehrlich-Schwoebel barriers we find that there is indeed a range of parameters where the surface quality in PLD is better than in MBE. However, since the improvement is weak and occurs only in a small range of parameters we conclude that deposition in pulses alone cannot explain the experimentally observed smoothness of PLD-grown surfaces.