Institute of Ohysical Chemistry Ilie Murgulescu Singlecrystalline semiconductor

Institute of Ohysical Chemistry “Ilie Murgulescu” Singlecrystalline semiconductor electrodes modified with monolayer protected gold clusters ID_35/2008: Research Project sponsored by the National University Research Council - Executive Agency for Higher Education and Research Funding (CNCSIS-UEFISCSU) No 500/2009. Project Director: Dr. Valentina Lazarescu

Project Summary n The poor chemical stability of semiconducting surfaces along with their high density of surface states is considered one of the major impediments in developing large scale device applications. Therefore, much effort has been done in order to improve the electronic properties of these surfaces by their chemical modification. Thiol selfassembled monolayers turned out to be among the most promising candidates. An extensive research has been lately focused on Au clusters embedded in a thiolate monolayer, the so-called monolayer protected clusters, interest in this field being justified by the potential utility of these materials in biochemistry, chemical sensors and microelectronic device fabrication. The design of such structures with specific functions and properties is possible only by understanding the mechanism of the electronic interactions and their role in the self-assembly process. This project explores the effects of the self-assembled monolayers formed by 4, 4'thiobisbenzenethiol and colloidal Au on the electronic properties of Ga. As(hkl) and Si(hkl) electrodes as reflected in their electrochemical and non-linear optical properties. Our team has a good expertise in studying the surface state-and fieldeffects at semiconductor/solution interface by Electrochemical Impedance Spectroscopy and Second Harmonic Generation. Information concerning the passivation efficiency supplied by cyclic voltammetry with stationary and rotating disc electrodes combined with that referring to the organic layer conductivity and transport properties explored by Scanning Electrochemical Microscopy (technique capable of probing surface reactivity of materials at microscopic scales) provide a deep insight into this complex interface architecture. AFM/STM and XPS studies will furnish further data on surface morphology and chemical composition. SHG and SECM investigations will be performed within the existing cooperation framework, at Ulm University and Rennes University, respectively.

Reserch Team Surname and first name Year of birth Scientific title Doctorate 1 Enache Mirela 1973 Senior Researcher III yes 2 Anastasescu Mihai 1971 Senior Researcher III yes 3 Preda Loredana 1975 Senior Researcher yes 4 Scurtu Rares 1975 - yes 5 Toader Ana Maria 1978 - Ph D Student

Budget Nr. crt. Budget category 2009 1. Staff expenses 2. Indirect expenses 18513. 68 lei 3. Mobilities 10204. 80 lei 4. Logistic costs 39218. 34 lei 5. Total 92568. 44 lei 24631. 62 lei 2010 2011 Total

Project objectives in 2009 n Preparation and characterization of Ga. As(hkl) electrodes modified with 4, 4’thiobis-benzenethiol (TBBT) n Studies on the TBBT effects on the electronic properties of the Ga. As(hkl) electrodes by electrochemical impedance spectroscopoy (EIS) n Evaluation of the redox properties of the TBBT-modified Ga. As(hkl) electrodes

Scientific contributions based on the results obtained in 2009 n 1. V. Lazarescu, R. Scurtu, M. F. Lazarescu, A. M. Toader, E. Volanschi, n n Passivation Effects of 4, 4’ Thio-bis-benzene-thiolate Adsorbed Layers on Semiconducting Electrodes, oral presentation at 60 th Annual Meeting of the International Society of Electrochemistry, Beijing, 15 -22 Aug. 2009, invited for publication in Electrochimica Acta 2. Rareş Scurtu, Mihail Lăzărescu, Valentina Lăzărescu, Surface Statesand Field-Effects at Bare and Thiolate Covered Ga. As(111)A Electrodes, poster presented at 60 th Annual Meeting of the International Society of Electrochemistry, Beijing, 15 -22 Aug. 2009 3. V. Lazarescu, R. Scurtu, M. F. Lazarescu, A. M. Toader, E. Volanschi, E. Santos, H. Jones, G. Götz, P. Bäuerle Surface States- and Field Effects at Thiolate-Covered Ga. As(110) Electrodes, oral presentaion at 5 th Kurt Schwabe Symposium, Erlangen, 24 -28 Mai 2009 4 V. Lazarescu, R. Scurtu, M. F. Lazarescu, A. M. Toader, E. Volanschi, E. Santos SHG- and EIS-investigations on thiolate-covered Ga. As(110) electrodes, oral presentation at Journees d’Electrochimie, Sinaia, 6 -10 iulie 2009 5. A. M. Toader, M. Lăzărescu, V. Lăzărescu, E. Volanschi, L'électrochimie de l'hémine sur des électrodes de Ga. As fonctionnalisées avec 4, 4 thiobisbenzènethiol, poster at Journees d’Electrochimie Sinaia, 6 -10 iulie 2009