New growth mode through decorated twin boundaries

Area of Science:

• Surface science
• Materials science
• Condensed matter physics

Background:

• Understanding thin film growth is crucial for developing advanced materials.
• Iridium (Ir) thin films exhibit unique properties relevant to catalysis and electronics.
• Controlled growth of specific crystalline structures, like twinned films, is challenging.

Purpose of the Study:

• To investigate the growth modes of iridium thin films on an Ir(111) substrate.
• To elucidate the transition from layer-by-layer growth to defect-dominated growth.
• To understand the atomistic mechanisms behind the formation of twinned stacking in Ir films.

Main Methods:

• Scanning tunneling microscopy (STM) for atomic-scale surface imaging.
• Low energy electron diffraction (LEED) for surface structure analysis.
• In-situ observation during thin film deposition.

Main Results:

• A transition from layer-by-layer to defect-dominated growth was observed.
• The growth exhibited a fixed lateral length scale and increasing roughness.
• The majority of the film formed stable, twinned stacking.
• This twinned structure resulted from avoiding intrinsic stacking faults.

Conclusions:

• The growth mode of Ir thin films on Ir(111) is sensitive to defect formation energetics.
• Energetic favorability of twin faults drives the transition to twinned stacking.
• The study provides atomistic insights into defect kinetics during thin film growth.