Scientific Results

Understanding adhesion of gold conductive films on sodium alginate by photoelectron spectroscopy

Year: 2019

Authors: Capelli R., Maccagnani P., Dinelli F., Murgia M., Bertoldo M., Montecchi M., Doyle B. P., Carleschi E., Pasquali L.

Autors Affiliation: 1 Dipartimento di Ingegneria E. Ferrari, Università di Modena e Reggio Emilia, Via Vivarelli 10,
41125 Modena, Italy
2 CNR – Istituto Officina dei Materiali, S.S. 14, km 163.5 in Area Science Park, 34012 Trieste, Italy
3 Department of Physics, University of Johannesburg, PO Box 524, Auckland Park, 2006, South
Africa
4 CNR – Istituto per la Microelettronica e Microsistemi, via P. Gobetti 101, 40129 Bologna, Italy
5 CNR – Istituto Nazionale di Ottica, via G. Moruzzi 1, 56124 Pisa, Italy
6 CNR – Istituto per lo Studio dei Materiali Nanostrutturati, via P. Gobetti 101, 40129 Bologna, Italy
7 CNR – Istituto per la Sintesi Organica e la Fotoreattività, via P. Gobetti 101, 40129 Bologna, Italy

Abstract: Ultrathin layers of gold, from 2 to 25 nm of nominal coverage, have been deposited on sodium-alginate biopolymer foils applying two alternative approaches: low power sputtering and thermal evaporation. The morphology of the deposited layers was obtained by means of atomic force microscopy. In the early stages of growth, thermal evaporation gives rise to a top surface resembling the underlying substrate, whereas low power sputtering produces a topography characterized by smoother areas. This indicates that the film growth occurs in different ways. X-ray photoelectron spectroscopy with two photon energies, corresponding to Al Kα and Ag Lα photons, was used to get information on the chemistry at the interface and on the degree of intermixing between Au and sodium-alginate. While no chemical modifications with respect to the bare materials could be detected, the evolution of the intensities of the relevant core levels of Au and sodium alginate (Au 4f and Na 1s in particular) indicated a strong intermixing in the case of films deposited by low power sputtering. This is further supported by optical measurements. The observed behaviour can be correlated with the enhanced adhesion of sputtered films compared to thermally evaporated ones.

Journal/Review: THIN SOLID FILMS

Volume: 690      Pages from: 137535  to: 137540

KeyWords: Sputtering deposition, Thermal evaporation, Gold thin films, Biopolymer, X-ray photoelectron spectroscopy
DOI: https://doi.org/10.1016/j.tsf.2019.137535