Applied Surface Science 257 (2011) 7184–7189 Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Field emission studies of silver nanoparticles synthesized by electron cyclotron resonance plasma Vishwas Purohit a,∗ , Baishakhi Mazumder b , A.B. Bhise a , Pankaj Poddar b , D.S. Joag a , S.V. Bhoraskar a a Department of Physics, University of Pune, Pune 411007, India b Physical & Materials Chemistry Division, National Chemical Laboratory, Pune 411008, India article info Article history: Received 26 July 2010 Received in revised form 10 February 2011 Accepted 15 March 2011 Available online 22 March 2011 Keywords: Cold plasma Nanoparticles Field emission Thin film abstract Field emission has been studied for silver nanoparticles (25–200 nm), deposited within a cylindrical silver target in an electron cyclotron resonance (ECR) plasma. Particle size distribution was controlled by optimum biasing voltages between the chamber and the target. Presence of non-oxidized silver was confirmed from the X-Ray diffraction analysis; however, thin protective layer of oxide was identified from the selective area electron diffraction pattern obtained with transmission electron microscopy. The silver nanoparticles were seen to exhibit hilly pointed like structures when viewed under the atomic force microscopy (AFM). The emissive properties of these particles were investigated by field emission microscopy. It is found that this technique of deposition is ideal for formation of nanoparticles films on different substrate geometries with size controllability as well as its application to emission devices. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Reduction in the crystallite size towards nanometers produces substantial changes in the optical, thermal, dielectric, structural, magnetic and other properties of the material. This is often seen in terms of increase in hardness values, higher electrical resis- tivity, lower thermal conductivity, larger specific heat as well as higher thermal expansion coefficient to name a few [1–3]. Silver nanoparticles exhibit many unique chemical and physical proper- ties, and have applications in many fields, such as optical devices [4,5] gas sensors [6,7] and catalytic applications [8,9]. They have a large application base in antibacterial studies. Silver nanopar- ticles as well as ions have an oligodynamic effect meaning that silver is capable of causing a bacteriostatic (growth inhibition) or a bactericidal (antibacterial) impact on various species of bacteria [10,11]. Various methods, such as chemical reduction [12–17], photo- chemical or chemical reduction [18,19], pulsed laser deposition [20] and sonochemical method [21], are being used to prepare sil- ver powders in the nanodimensional regime. Irradiation techniques are also used for silver nanoparticles creation such as those used by Korchagin et al. [22] who have produced silver nanopowder (70–80 nm) by irradiating silver in an electron accelerator. Mal- ∗ Corresponding author at: Groupe de Physique des Matériaux (GPM), Avenue de l’Université - BP 12, 76801St. Etienne du Rouvray, Cedex-France. Fax: +33 232 955 032. E-mail address: viswas.purohit@univ-rouen.fr (V. Purohit). iszewska et al. have also studied the biological synthesis of silver nanoparticles by using fungus mediated synthesis and showed nanoparticles of sizes varying from 10 to 100 nm in a solution [23,24] However, a monodispersed nanocrystalline array of metallic sil- ver nanoparticles on a suitable substrate is very useful for display device related applications, which are based on field emission tech- nology. To obtain a monodispersed layer, chemical techniques like sol–gel or co-precipitation are unsuitable as they cause an increase in particle size due to thermal agglomeration. Hollow cathode discharge based chemical sputtering within an electron cyclotron resonance (ECR) plasma is a unique method in which nanocrystalline films can be formed at normal temperatures without the use of post annealing treat- ment and in controlled conditions. Smooth continuous films of nanomaterial with good adhesion can be formed on a wide range of substrates. Zinc nanowires [25] and molyb- denum particles [26] have been previously formed by this method. The domain of field electron emission from nanostructured materials has taken deep roots in the research and analysis of nano materials. Application of these emitters in flat panel dis- play devices and as electron sources in vacuum microelectronic devices have generated the growing interest in the synthe- sis and characterization of nanostructured materials and their study as field electron emitters. The present work is aimed at obtaining uniform arrays of silver nanoparticles on planar as well as cylindrical substrates and to study their field emission properties. 0169-4332/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2011.03.088