Applied Surface Science 257 (2011) 5245–5249 Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication Ludovic Rapp a,∗ , Christophe Cibert a , Sébastien Nénon b , Anne Patricia Alloncle a , Matthias Nagel c , Thomas Lippert d , Christine Videlot-Ackermann b , Frédéric Fages b , Philippe Delaporte a a Laboratoire LP3 (Lasers, Plasma et Procédés Photoniques) – UMR 6182 CNRS – Université de la Méditerranée – Campus de Luminy C917, 13288 Marseille Cedex 09, France b CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) – UPR 3118 CNRS – Université Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09, France c Empa, Swiss Federal Laboratories for Materials Testing and Reasearch, Laboratory for Functional Polymers, Überlandstrasse 129, 8600 Dübendorf, Switzerland d Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI, Switzerland article info Article history: Received 11 June 2010 Received in revised form 30 September 2010 Accepted 29 October 2010 Available online 5 November 2010 Keywords: Laser-induced forward transfer Organic semiconductor Shadowgraphic visualizations Nanosecond Picosecond abstract Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The interest in organic thin-film transistors (OTFT) has been increasing considerably over the past few years, because they offer unique opportunities in low-cost microelectronics. Laser-based processes offer versatile alternatives for the deposition of thin films in organic devices operating on flexible supports where the usual techniques cannot be used due to a lack of solubility, or in the case of complex device architectures fabrication. The LIFT [1] process consists of transfer of a piece of a thin film previously deposited on a transparent donor substrate onto an acceptor substrate usually using a single laser pulse. This sim- ple, single step, direct printing technique offers the ability to make localized deposition of material. It has been successfully applied for a wide broad range of material such as metals [2], nanotubes [3], powder [4], liquids [5], organics [6] and biomaterials [7]. The patterned deposition of thin organic semiconductor films is essential for the development of organic electronic devices. The p- type oligomer DS4T is a remarkably efficient semiconductor in the OTFT configuration but it does not possess the required solubility ∗ Corresponding author. Tel.: +33 04 91 82 95 13; fax: +33 04 91 82 92 89. E-mail address: rapp@lp3.univ-mrs.fr (L. Rapp). properties. It is a non-commercial semiconductor synthesized and purified by sublimation by the CINaM laboratory [8]. In this paper, we study the laser printing of this oligomer using the LIFT technique and discuss the dynamics of the transfer. 2. Experimental setup In order to understand the mechanisms of the ejection and to determine optimal conditions of transfer, time-resolved visu- alizations have been carried out. This technique has already been achieved to study ejection and transfer of various materials [9–12]. Two different pulsed lasers have been used: - Krypton fluoride (KrF) (EMG203MSC Lambda Physik) 35 ns @ 248 nm, 1–100 Hz, 0.5 J. - Neodyme doped yttrium aluminum garnet (Nd:YAG) (Leopard S10/20 Continuum) operating on its third harmonic: 50 ps @ 355 nm, 10 Hz, 0.04 J. Pulse duration has an influence on the heat diffusion, less ther- mal losses can be expected using the ps laser. The other motivation is to study the effect of the laser beam of a flat (ns laser) and a Gaus- sian (ps laser) energy profile on the flyer ejection and shape. The LIFT experimental setup has already been described elsewhere [13]. 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.10.147