Surface Science Letters 262 (1992) L139-L143 North-Holland zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBAsurface science letters zyxwvutsrqpon Surface Science Letters Reaction between copper dipiva~oy~~~thanat~ Cu( DPM) 2 and H,O adsorbed on SrTiO,( 100) Tokihisa Hikita, Rika Sekine, Takashi Hanada Research Laboratory of Engineer&g Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, &an and Maki Kawai The Institute of Physical and Chemical Research (HKEN~, 2-1 Hirosawa, Wako-shi, Saitama 351-01, Japan Received 17 June 1.991; accepted for publication 30 October 1991 Selective reaction of copper dipivaloylmethanate (Cu(DPM),, P-diketonate complex) with H,O adsorbed on the SrTiO,(lOO) surface is investigated. Adsorption of Ha0 on SrTiOs(100) occurs on Ti3+ sites produced by prior Arf ion bombardment. It is found that the ~-diketonate complex, Cu(DPM),, reacted selectivety with the adsorbed Ha0 at room temperature. Further reaction of the adsorbed Cu(DPM)a with Ha0 vapor results in the removal of the ligand, DPM, leaving elemental copper on the surface. 1. Introduction Selective adsorption or reaction on surfaces helps us to realize the atomically dispersed and controlled deposition of thin films. Selective reac- tions are also indispensable in designing self- terminating deposition systems. In the latter ap- plication the reaction between surface functional groups and organometallic compounds or com- plexes is expected to give us information about the atomically controlled deposition mechanism itself. Finally surface reaction has a great advan- tage in that the mount of deposited metals can be controlled by adjusting the amount of surface functional groups. On fine particles of SiO,, a selective and stoi- chiometric adsorption of P-diketonate com- pounds, copper dipivaloylmethanates (Cu(DPM),; 2,2,6,6-tetramethyl-3,5-heptadione) with surface hydroxyl group (OH) is reported [1,21. In this reaction, H atoms from the surface OH groups move into the DPM ligand, and the interaction between the adsorbed ligand and the surface 0 is considered to be the cause of the stoichiometrical adsorption of Cu(DPM), and the surface hy- droxyl group [1,2]. The removal of the ligand from the adsorbed CufDPM), is realized by H,O vapor reacting with the adsorbate. A simifar reac- tion is expected to occur on the surface of the oxide single crystal, where the OH groups also exist or subsequently adsorb. It has been reported that the SrTiO, surface is active for the adsorption of H,O when it has Ti3+ sites on the surface [3-51. The SrTiO~(l~) surface with adsorbed H,O is considered to show a similar reactivity with Cu(DPM), to that of the SiO, surface with OH groups. In this Letter, the reactivity of Cu(DPM), with H,O adsorbed on the SrTiO,(lOO) surface is reported. We also dis- cuss on the decomposition of Cu(~PM)~ ad- sorbed on the SrTiO,(lOO) surface via the reac- tion with H,O vapor. 0039-6028/92/$0500 0 1992 - Elsevier Science Publishers B.V. All rights reserved