Maria Dinescu

tel: 40 21 457 4470
fax: 40 21 457 4243
E-mail: dinescum@ifin.nipne.ro

Area of Expertise

Laser materials processing, thin film growth, laser processing of thin films and heterostructure, ferroelectrics, piezoelectrics, composite materials, biocompatibles, advanced laser techniques for soft matter processing

Biography

I graduated in Bucharest (1978) and I worked in the field of Laser Materials Processing, Thin Film Growth. My present interest concerns laser processing of thin films and heterostructure: ferroelectrics, piezoelectrics, composite materials, biocompatibles, advanced laser techniques for soft matter processing. I coordinate my group in two international projects: Co-Director of the NATO SfP Project 97-1934, "Laser Based Clean Technologies for Smart Sensor Applications," (1999-2002). Romanian Coordinator of IST-2001-33326 "Piezoelectric sensor arrays for biomolecular interactions and gas monitoring" (PISARRO) project (2002-2004). Editor of three books and author of two chapters published in books: F. Craciun, P. Verardi, M. Dinescu, "Piezoelectric thin films: processing and properties", Handbook of Thin Film Materials, Vol. 3. Ferroelectric and Dielectric Thin Films, Ed- H.S. Nalwa, Academic Press, (2002), pp. 231-309; F. Craciun and M. Dinescu, "Pulsed Laser Deposition of Piezoelectric Thin Films" R.W. Eason, (ed.), Pulsed Laser Deposition of Thin Films, John Wiley & Sons, New York, 2005 (in press).

Lecture Title(s)

Pulsed Laser Deposition of Functional Oxide Thin Films
Pulsed Laser Deposition (PLD) is an emerging technique for thin film deposition. It technique consists in material removal by bombarding the surface of a target whit short energetic pulses of a focalized laser beam of proper wavelength (laser ablation). This process takes place in a vacuum chamber where a gas is held at constant pressure. The substrate to be coated is placed few centimeters apart of the target facing the top of the plasma plume. The condensation of the particles ejected from the target produces the growth of a thin film on the substrate surface. The deposited film composition can be the same as the target, if the gas atmosphere is inert, or a compound depending on the reactive gas introduced in the deposition chamber. The possibility to transfer complicated stoichiometries directly from the target to a collector situated at a certain distance and position with respect to the target pushed this method in a top position starting with the discovery of the high temperature superconductors, in the second part of 80' decade. Different classes of materials, as metals, semiconductors, and dielectrics were successfully deposited by pulsed laser deposition (PLD) in vacuum or in different inert or chemically active atmosphere. The technique itself is simple and versatile and has some particular advantages: i) synthesis of metastables materials that cannot by produced by "standard" techniques; ii) fabrication of films from species that are generated only during pulsed laser ablation; iii) the possibility of transferring complicated stoichiometries from bulk into thin film (congruent ablation), as in the case of oxides as high Tc superconductors, piezoelectric and ferroelectric compounds, biocompatible materials (hydroxyapatite) etc.; iv) the laser energy source is external to the system therefore it is a "clean" reactor; v) the laser beam is incident on a small zone on the target surface which results in high efficiency, control and flexibility of the process; vi) no charge effects appears; vii) no "memory" reactor: the possibility to deposit heterostructures by changing the target and/or the reactive gas as well; vii) in some cases it is a single step process: synthesis and deposition, ZnO from Zn in O2, ZrO2 from Zr in oxygen; viii) decreases the deposition temperature and, sometimes, no subsequent thermal treatments are required.

Laser Based Techniques for Soft Matter Processing
Laser based techniques are recently emerging as attractive solution for soft matter processing. One of these techniques is Matrix Assisted Pulsed Laser Evaporation (MAPLE). The target consisting of the material (usually 0.1-2 wt%) dissolved in a solvent, is cooled down to a solid state, and it is evaporated using a laser. The material is collected on a nearby substrate parallel to the target, and the solvent is eliminated through the vacuum system. Compared to PLD, MAPLE is a gentle deposition technique for polymers and organic films; the laser energy is absorbed only by the solvent and therefore the bond dissociation and chemical modification can be avoided. A similar adjusted method, Matrix Assisted Pulsed Laser Evaporation Direct Write (MAPLE DW) was demonstrated to be an attractive laser based approach for developing tissue engineered constructs and other cell-based assemblies.