Ž . Applied Surface Science 157 2000 52–60 www.elsevier.nlrlocaterapsusc Structural and chemical investigation of surface and interface of multilayer optical coatings deposited by DIBS M. Alvisi a, ) , L. Mirenghi b , L. Tapfer b , A. Rizzo b , M.C. Ferrara b , S. Scaglione c , L. Vasanelli a a INFM, c r o Dipartimento Scienza dei Materiali, UniÕersita di Lecce, Õia Arnesano, 73100 Lecce, Italy ` b PASTIS-Centro Nazionale Ricerca e SÕiluppo Materiali, S.S.7 Appia km.712, 72100 Brindisi, Italy c DiÕisione DispositiÕi Ottici, ENEA CRE Casaccia, 00060 Rome, Italy Received 17 September 1999; accepted 26 October 1999 Abstract The investigation of the surface and interface of a multilayer coating is a key factor for producing high quality optical device. In this work, we present a non-destructive technique as X-ray reflectivity to study deeply the chemical and structural quality of the multilayer. XPS depth profile analysis and AFM images have been used to evaluate the chemical intermixing and the surface roughness in order to verify the X-ray results. q 2000 Elsevier Science B.V. All rights reserved. PACS: 32.79.W; 61.10.Kw; 81.15 Keywords: X-ray reflectivity; X-ray photoelectron spectroscopy; Oxide coatings; Optical multilayer 1. Introduction In order to satisfy the increasing demand of high quality optical devices for laser optics, multilayer UV coatings have considerably improved their per- w x formances in recent years 1–4 . The major trend in projecting antireflection and partially reflecting mul- tilayers is to use no more than two materials of high wx and low refractive index, respectively 5 . ) Corresponding author. PASTIS-Centro Nazionale Ricerca e Sviluppo Materiali, S.S.7 Appia km.712, 72100 Brindisi, Italy. Tel.: q 0039-831-507405; fax: q 0039-831-507379. Ž . E-mail address: alvisi@p1.cnrsm.it M. Alvisi . The device has to satisfy many important require- ments such as high damage resistance, good mechan- ical properties, good abrasion resistance together with the pure optical constraints. In particular, the laser damage resistance and the mechanical stability are the principal requisites of a good interference-coat- ing device. These properties are determined by the Ž chemical composition of the layers low optical ab- . sorption and by the structural properties of each layer as well as of the entire device. Each layer should be free of structural defects and must exhibit a high-thickness homogeneity. The surface of the coating should have a low roughness and the deep interfaces should be abrupt. Interface roughness and elemental intermixing at interfaces may influence the optical characteristics and device performance and 0169-4332r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0169-4332 99 00520-6