Journal of Crystal Growth 285 (2005) 191–200 Gadolinium oxide thin films by atomic layer deposition Jaakko Niinisto¨ a,Ã , Nikolina Petrova b , Matti Putkonen a , Lauri Niinisto¨ a , Kai Arstila c , Timo Sajavaara c,1 a Laboratory of Inorganic and Analytical Chemistry, Helsinki University of Technology (TKK), P.O. Box 6100, FIN-02015 Espoo, Finland b Department of General and Inorganic Chemistry, Sofia University, BL-1164 Sofia, Bulgaria c Accelerator Laboratory, University of Helsinki, P.O. Box 43, FIN-00014 Helsinki, Finland Received 15 April 2005; received in revised form 25 July 2005; accepted 1 August 2005 Available online 19 September 2005 Communicated by R. Fornari Abstract Gadolinium oxide thin films have been deposited on Si(1 0 0) by atomic layer deposition (ALD) using as precursors either a b-diketonate-type chelate, namely Gd(thd) 3 (thd ¼ 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone or a true organometallic (CpCH 3 ) 3 Gd (Cp ¼ cyclopentadienyl, C 5 H 5 ) together with water. Self-limiting ALD growth mode was detected for the Gd(thd) 3 /O 3 process at 300 1C with a growth rate of 0.3 A ˚ /cycle. In the case of the (CpCH 3 ) 3 Gd/ H 2 O process, partial decomposition of the metal precursor affected the film growth mechanism. However, at 250 1C, the uniform films obtained from (CpCH 3 ) 3 Gd and H 2 O showed almost an ideal stoichiometry with low impurity contents (e.g. 0.5 at% of C) as analyzed by time-of-flight elastic recoil detection analysis (TOF-ERDA). X-ray diffraction data indicated that Gd 2 O 3 films obtained by the Cp-based process were crystalline with cubic C-type structure when deposited even at 150 1C. The strongest reflection changed from (4 0 0) to (2 2 2) at deposition temperatures around 200 1C. Oxygen-rich films grown by the Gd(thd) 3 /O 3 process were amorphous at deposition temperatures below 250 1C but crystalline with (4 0 0) dominant reflection at temperatures exceeding 250 1C. The films were smooth with both processes at the optimized deposition temperatures. In addition, the dielectric properties were analyzed showing effective permittivity of about 13 for the (CpCH 3 ) 3 Gd/H 2 O-processed Gd 2 O 3 films. r 2005 Elsevier B.V. All rights reserved. PACS: 77.55.+f; 79.60.Dp; 81.15.Gh Keywords: A3. Atomic layer deposition; A3. Chemical vapor deposition processes; B1. Gadolinium compounds; B1. Oxides; B2. Dielectric materials ARTICLE IN PRESS www.elsevier.com/locate/jcrysgro 0022-0248/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2005.08.002 Ã Corresponding author. Tel.: +35894512610; fax: +3589462373. E-mail address: Jaakko.Niinisto@hut.fi (J. Niinisto¨). 1 Currently at: Physics Department, University of Jyva¨skyla¨, P.O. Box 35, FIN-40014, Finland.