Oscillatory interaction between O impurities and Al adatoms on Al(1 1 1) and its effect on nucleation and growth C. Polop a, * , H. Hansen a , W. Langenkamp a , Z. Zhong a , C. Busse a , U. Linke b , M. Kotrla c , Peter J. Feibelman d , T. Michely a a I. Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany b ISG 3, Forschungszentrum Ju ¨ lich, 52425 Ju ¨ lich, Germany c Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic d Sandia National Laboratories, Albuquerque, NM 87185-1413, USA Received 11 August 2004; accepted for publication 8 November 2004 Available online 24 November 2004 Abstract We present a combined experimental and theoretical study of submonolayer growth in the presence of predeposited immobile impurities. Scanning tunneling microscopy measurements of Al/Al(1 1 1) epitaxy in the presence of oxygen adsorbates show that immobile O impurities influence all aspects of the early stages of homoepitaxial growth on Al(1 1 1). Possible scenarios for modified growth are investigated using kinetic Monte Carlo simulations. Dependences of island density on temperature, impurity concentration and strength and type of adatom–impurity interaction are compared. The comparison shows that the morphology of the growing Al film cannot result from only one interaction type: attractive or repulsive. An oscillatory interaction, suggested by ab initio calculations, is proposed to explain the behavior of the system. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Scanning tunneling microscopy; Growth; Nucleation; Surface diffusion; Aluminum; Adatoms; Density functional calcul- ations; Monte Carlo simulations 1. Introduction Understanding and control of thin film growth modes are central to materials science, since the performance of thin film-based devices is deter- mined by their structure and defect concentration. 0039-6028/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.susc.2004.11.010 * Corresponding author. Tel.: +49 241 802 7209; fax: +49 241 802 2331. E-mail address: polop@physik.rwth-aachen.de (C. Polop). Surface Science 575 (2005) 89–102 www.elsevier.com/locate/susc