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Role of growth temperature on nanostructure and field emission properties of PLD thin carbon films
Authors:C Scilletta  S Orlando  M Servidori  E Cappelli  G Conte  P Ascarelli
Institution:(1) CNR-ISC, Montelibretti, via Salaria Km 29.3, P.O.B. 10, 00016 Monterotondo, Rome, Italy;(2) CNR-IMIP, Potenza, 85050 Tito Scalo, Potenza, Italy;(3) CNR-IMM, Bologna, Via P. Gobetti 101, 40129 Bologna, Italy;(4) Department of Electronic Engineering and CNISM, University of Rome “Roma Tre”, Via della Vasca Navale 84, 00146 Rome, Italy
Abstract:Thin carbon films have been deposited in vacuum (∼10−4 Pa) on Si substrates by pulsed laser ablation of a graphite target using a Nd:YAG laser operating in the near infrared region (λ=1064 nm). The samples have been deposited at different substrate temperatures (T sub) ranging from room temperature (RT) to 800°C. X-ray diffraction analysis established the progressive formation of nanosized graphene structures as T sub increased. In fact, film structure evolves from almost amorphous to nanostructured phase characterized by graphene layers oriented perpendicularly to the film plane. The film density, evaluated by X-ray reflectivity measurements, is strongly affected by T sub. At RT the film density is similar to the graphite one, while it decreases at higher T sub. The electrical properties of the samples have been characterized by field emission measurements. The parameters describing the emitter properties (threshold field E th and field enhancement factor β) have been evaluated using variable anode-to-cathode distance method. Samples deposited at low T sub have shown the best emission properties, presenting lower E th and larger β values than those deposited at higher T sub. This is mainly attributed to the sensible density variation, which is in competition with the slighter augment of mean nanoparticle size.
Keywords:PACS" target="_blank">PACS  81  15  Fg  61  48  De  79  70  +q
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