Evidence for enhanced desorption of hydrogen atoms from a Si(1 0 0) surface induced by slow highly-charged ions J. Deiwiks a , G. Schiwietz b , S.R. Bhattacharyya c, * , G. Xiao d , R. Hippler a a Institut fu ¨ r Physik, Ernst-Moritz-Arndt-Universita ¨ t Greifswald, Domstraße 10a, D-17487 Greifswald, Germany b Hahn-Meitner-Institut Berlin, Glienicker Straße 100, D-14109 Berlin, Germany c Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064, India d Institute of Modern Physics, Nanchang Road 509, 730 000 Lanzhou, China Received 27 January 2006; received in revised form 6 April 2006 Available online 13 June 2006 Abstract We report evidence for an enhanced desorption of hydrogen atoms from a Si(1 0 0) surface bombarded by 30 keV Xe q+ (q = 6–22) ions. The measured desorption yield amounts to 0.76 and 2.2 hydrogen atoms per incident Xe 10+ and Xe 18+ ion, respectively. For under- standing the behaviour of hydrogen desorption from Si, another experiment was carried out to see the hydrogen signals as a function of time for about 140 min after deliberately introducing hydrogen into the target chamber and then shut off the valve. The results are dis- cussed in the light of potential sputtering which essentially dominates for ions at higher charge states and the interpretation is supported by theoretical estimates. Ó 2006 Elsevier B.V. All rights reserved. PACS: 79.20.Rf; 79.20.Ne; 79.90.+b Keywords: Desorption; Hydrogen; Highly-charged ions; Xenon; Electronic sputtering 1. Introduction Various new effects occur during the bombardment of solid surfaces with highly-charged ions (HCI), for example, an increased erosion of the surface caused by the large potential energy carried by the incident HCI and the for- mation of hollow atoms [1–6]. In particular, the so-called potential sputtering rather than the usual kinetic sputtering is presently attracting considerable interest [7] for its possi- ble applications in technology related to delicate sputter cleaning, fabricating nano-structures or material modifica- tions in nano-scale domain [8]. The field is also promising for its importance in understanding fundamental mecha- nism of highly-charged ion interaction with solid surfaces [9]. The Si surface with hydrogen is a unique combination for the investigation of adsorption and desorption of mol- ecules from semiconductor surfaces. Hydrogen on Si at a low coverage forms monohydrate and keeps the Si surface protected from other contaminations. The characteristics of thermal desorption of hydrogen show interesting fea- tures [10] that have attracted more researches [11–14] on it. It is known that atomic hydrogen adsorbs readily on Si by saturating the dangling bonds and forming Si–H bonds, but the sticking co-efficient of molecular hydrogen is extremely low; as low as 10 9 at room temperature [15]. It is likely, therefore, that the desorbed hydrogen from Si is mostly comprising of the molecular component. There are reports on the desorption studies of hydrogen from Si by a number of methods. Soukiassian et al. [11], in their scanning tunneling microscopy study, showed that atomic-scale desorption of hydrogen from Si(1 0 0)-(2 · 1) surface follows a power law with tunnel current in the 0168-583X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2006.04.069 * Corresponding author. Tel.: +91 33 23375345; fax: +91 33 23374637. E-mail address: satyar.bhattacharyya@saha.ac.in (S.R. Bhattachar- yya). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 248 (2006) 253–258 NIM B Beam Interactions with Materials & Atoms