Using differential evanescent light intensity for evaluating profiles and growth rates in KrF laser photodeposited nanostructures G. Socol Æ E. Axente Æ M. Oane Æ L. Voicu Æ A. Dinescu Æ A. Petris Æ V. Vlad Æ I. N. Mihailescu Æ N. Mirchin Æ R. Margolin Æ D. Naot Æ A. Peled Published online: 20 March 2007 Ó Springer Science+Business Media, LLC 2007 Abstract Pulsed Laser Photodeposition (PLP) of a-Se from aqueous colloid solutions with KrF laser at a wave- length of k = 248 nm has been performed. Nanometer thick layers were obtained on quartz substrates in contact with the solution for various Pulse Numbers (PN). Amor- phous Se layers, 5–20 nm thick, were obtained typically by 50–500 laser beam pulses of 7 (nsec) duration delivered at RR = 1 Hz with a total fluence of 370 mJ/cm 2 . The deposited nanometer morphology was analyzed by a Dif- ferential-Evanescent Optical Microscopy method and Scanning Electron Microscopy (SEM). The observed leaking electromagnetic field from the waveguide sub- strates was used to evaluate the thickness profile and growth rate of photodeposited a-Se. Capturing the differ- ential evanescent light leaking image, yielded the PLP nanostructures profiles in the deposited zone. Using this technique in combination with SEM microscopy allowed us to estimate the structural properties of the ultra-thin a-Se nano-structures. 1 Introduction Similar to common photographic methods, photodeposition (PD) from the solutions [1] can be used for realizing var- ious thin film patterns, of sub-microscopic thicknesses i.e. 5–500 (nm) to produce various spatially distributed com- ponents for optical applications such as described in [2, 3]. The one step, direct PD laser writing method [1] from solutions eliminates the time consuming steps encountered in standard lithography, allowing in addition the flexibility of varying in situ the thin films thickness. Thus, various patterns can be written in one step on solid interfaces which are in contact with the solution by laser scanning or pro- jection and mask imaging. The rate of the process for various materials depends on the laser wavelength, fluence and temperature of the photoreactor [1]. During PD [4] nanometer particles appear in the irra- diated zones of any transparent substrates, such as quartz in this investigation. In this work, Pulsed Laser Photodeposition (PLP) from colloid solutions onto quartz substrates using a KrF laser beam of 248 nm UV irradiation has been investigated. In contrast to previous CW lasers PD using UV short pulses of the order on nanoseconds creates photodeposited patterns of material on the substrates during very short times of the order of nanoseconds not allowing diffusion and redistribution flow of material on the surface [5]. However these ultra thin materials of nanometer thick- nesses cannot be evaluated by simple optical transmission methods. We used in this work the sensitive evanescent method for nanometer particles investigation developing also a new phenomenological formalism to evaluate and estimate quantitatively deposited nanolayers profiles. We use the concept of differential-evanescent light intensity (DELI) extraction from waveguides by the nanosize G. Socol  E. Axente  M. Oane  L. Voicu  A. Petris  V. Vlad  I. N. Mihailescu Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Bucharest-Magurele, Romania A. Dinescu National Institute for Microtechnologies, PO Box MG-54, Bucharest-Magurele 77125, Romania N. Mirchin  R. Margolin  D. Naot  A. Peled (&) Electrical and Electronics Engineering Department, Photonics Laboratory, Holon Institute of Technology, 52 Golomb Str, Holon 58102, Israel e-mail: peledd@gmail.com 123 J Mater Sci: Mater Electron (2007) 18:S207–S211 DOI 10.1007/s10854-007-9203-y