Potential sputtering

Abstract

The potential energy stored in multiply charged ions is liberated when the ions recombine during impact on a solid surface. For certain target species this can lead to a novel form of ion-induced sputtering, which, in analogy to the usual kinetic sputtering, has been termed 'potential sputtering'. This sputtering process is characterized by a strong dependence of the observed sputtering yields on the charge state of the impinging ion and can take place at ion-impact energies well below the kinetic sputtering threshold. We summarize a series of recent careful experiments in which potential sputtering has been investigated for hyperthermal highly charged ions' impact on various surfaces (e.g. Au, LiF, NaCl, SiO(2), Al(2)O(3) and MgO), present the different models proposed to explain the potential sputtering phenomenon and also discuss possible applications of potential sputtering for nanostructure fabrication.

An investigation of secondary ion yield enhancement using Bin2+ (n=1, 3, 5) primary ions

“…For example, below q ϳ 25 the secondary ion yield from silicon surfaces increases linearly with incident (primary) ion charge. However, above this threshold, the secondary ion yields from silicon surfaces increases nonlinearly with the primary ion charge above q ϳ25 [14].…”

“…This potential arises when q electrons are removed from species A to create an A qϩ ion. For highly charged ions, such as Ar 9ϩ , this potential can be in the keV range [14]. When such an ion strikes the surface, it induces a variety of nonelastic processes within the sample.…”

“…They transfer energy and momentum to atoms in the sample, which are displaced from their original position and ejected into the vacuum [1,2]. For multiply charged primary ions there is a second possible interaction known as potential sputtering [14]. In addition to kinetic energy, primary ions also carry potential energy that can be large if the ion is highly charged.…”

Electronic Sputtering of Nanodimensional Hydrogenated Amorphous Carbon and Copper Oxide Thin Films

“…The energy threshold of electronic sputtering strongly depends on the ion and solid combination. Moreover, if the projectile ion is multiply charged and is moving slowly, a particular form of electronic sputtering can take place which has been termed as potential sputtering 3 . In this case, the potential energy stored in multiply charged ions (i.e., the energy necessary to produce an ion of this charge state from its neutral atom) is liberated when the ions recombine during impact on a solid surface (formation of hollow atoms).…”

“…In this case, the potential energy stored in multiply charged ions (i.e., the energy necessary to produce an ion of this charge state from its neutral atom) is liberated when the ions recombine during impact on a solid surface (formation of hollow atoms). Potential sputtering has only been observed for certain target species and requires a minimum potential energy 3 . Up till now kinetic sputtering has been established as an essential process for many technological applications, such as (i) thin film deposition, (ii) sputter etching, (iii) ion milling, (iv) mass spectroscopy analysis of materials, etc.…”