Step velocity tuning of SrRuO3 step flow growth on SrTiO3

TL;DR

This study investigates how controlling step velocity influences the stability of SrRuO3 thin film growth on SrTiO3 substrates, revealing a critical velocity that determines stable or unstable step flow regimes.

Contribution

It introduces a method to tune step flow stability in SrRuO3 growth by adjusting step velocity, highlighting the transition point and underlying stress-driven mechanisms.

Findings

Stable and unstable step flow regimes are identified.

A critical step velocity for transition is established.

Step bunching occurs below the critical velocity.

Abstract

Taking advantage of vicinal (001) SrTiO3 substrates with different mean terrace widths, the heteroepitaxial growth of SrRuO3 in the step flow mode has been mapped as a function of mean step velocity. Transition between stable and unstable step flow is shown to occur at a well-defined critical step velocity, with a step bunching instability observed below this threshold. The ability to pass from unstable to stable step flow during growth upon increasing the mean step velocity is demonstrated. This result is discussed in terms of a stress-based driving force for step bunching in competition with an effective step-up adatom current.