Probing timescales during back side ablation of Molybdenum thin films with optical and electrical measurement techniques

Opt Express. 2013 Jul 15;21(14):16431-43. doi: 10.1364/OE.21.016431.

Abstract

In this study we present a new measurement technique to investigate the timescales of back side ablation of conductive films, using Molybdenum as an application example from photovoltaics. With ultrashort laser pulses at fluences below 0.6 J/cm(2), we ablate the Mo film in the shape of a fully intact Mo 'disc' from a transparent substrate. By monitoring the time-dependent current flow across a specifically developed test structure, we determine the time required for the lift-off of the disc. This value decreases with increasing laser fluence down to a minimum of 21 ± 2 ns. Furthermore, we record trajectories of the discs using a shadowgraphic setup. Ablated discs escape with a maximum velocity of 150 ± 5 m/s whereas droplets of Mo forming at the center of the disc can reach velocities up to 710 ± 11 m/s.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Conductometry / methods*
  • Lasers*
  • Materials Testing / methods*
  • Membranes, Artificial*
  • Molybdenum / analysis
  • Molybdenum / chemistry*
  • Molybdenum / radiation effects*
  • Refractometry / methods*

Substances

  • Membranes, Artificial
  • Molybdenum