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Title: Dynamics of fast pattern formation in porous silicon by laser interference

Patterns are fabricated on 290 nm thick nanostructured porous silicon layers by phase-mask laser interference using single pulses of an excimer laser (193 nm, 20 ns pulse duration). The dynamics of pattern formation is studied by measuring in real time the intensity of the diffraction orders 0 and 1 at 633 nm. The results show that a transient pattern is formed upon melting at intensity maxima sites within a time <30 ns leading to a permanent pattern in a time <100 ns upon solidification at these sites. This fast process is compared to the longer one (>1 μs) upon melting induced by homogeneous beam exposure and related to the different scenario for releasing the heat from hot regions. The diffraction efficiency of the pattern is finally controlled by a combination of laser fluence and initial thickness of the nanostructured porous silicon layer and the present results open perspectives on heat release management upon laser exposure as well as have potential for alternative routes for switching applications.
Authors:
; ;  [1] ;  [2]
  1. Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid (Spain)
  2. Departament d'Òptica i Optometria, UPC, Violinista Vellsolà 37, 08222 Terrasa (Spain)
Publication Date:
OSTI Identifier:
22350949
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BEAMS; DIFFRACTION; EFFICIENCY; EXCIMER LASERS; INTERFERENCE; LAYERS; MELTING; NANOMATERIALS; NANOSTRUCTURES; POROUS MATERIALS; PULSES; SILICON; SOLIDIFICATION; THICKNESS; TRANSIENTS