Different W cluster deposition regimes in pulsed laser ablation observed by in situ Scanning Tunneling Microscopy

TL;DR

This study demonstrates how varying parameters in pulsed laser ablation can control different tungsten cluster deposition regimes on surfaces, enabling tailored surface modifications and film growth.

Contribution

It introduces a method to observe and control various cluster deposition regimes in situ using STM during pulsed laser deposition.

Findings

Different deposition regimes depend on gas pressure and target-to-substrate distance.

Cluster mobility influences aggregation and growth mechanisms.

Deposition parameters can be tuned for specific surface modifications.

Abstract

We report on how different cluster deposition regimes can be obtained and observed by in situ Scanning Tunneling Microscopy (STM) by exploiting deposition parameters in a pulsed laser deposition (PLD) process. Tungsten clusters were produced by nanosecond Pulsed Laser Ablation in Ar atmosphere at different pressures and deposited on Au(111) and HOPG surfaces. Deposition regimes including cluster deposition-diffusion-aggregation (DDA), cluster melting and coalescence and cluster implantation were observed, depending on background gas pressure and target-to-substrate distance which influence the kinetic energy of the ablated species. These parameters can thus be easily employed for surface modification by cluster bombardment, deposition of supported clusters and growth of films with different morphologies. The variation in cluster mobility on different substrates and its influence on aggregation and growth mechanisms has also been investigated.