Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF2(111) surface

El-Said, A.S.; Meissl, W.; Simon, M. C.; López‐Urrutia, J. R. Crespo; Lemell, C.; Burgdörfer, Joachim; Gebeshuber, Ille C.; Winter, H.; Ullrich, J.; Trautmann, C.; Toulemonde, M.; Aumayr, F.

doi:10.1016/j.nimb.2006.12.142

Cited by 50 publications

(30 citation statements)

References 34 publications

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“…Another threshold is expected to exist at still higher potential energy (higher charge state), which should correspond to a liquid-vapor phase transition (sublimation) [3]. While predicted in calculations [20] this threshold has so far not been unambiguously identified experimentally (although first indications indicate such a second threshold for CaF 2 [84]). …”

Section: Slow Highly Charged Ionsmentioning

confidence: 95%

Highly charged ion induced nanostructures at surfaces by strong electronic excitations

Wilhelm¹,

El-Said²,

Heller³

et al. 2015

Progress in Surface Science

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a b s t r a c tNanostructure formation by single slow highly charged ion impacts can be associated with high density of electronic excitations at the impact points of the ions. Experimental results show that depending on the target material these electronic excitations may lead to very large desorption yields in the order of a few 1000 atoms per ion or the formation of nanohillocks at the impact site. Even in ultra-thin insulating membranes the formation of nanometer sized pores is observed after ion impact. In this paper, we show recent results on nanostructure formation by highly charged ions and compare them to structures and defects observed after intense electron and light ion irradiation of ionic crystals and graphene. Additional data on energy loss, charge exchange and secondary electron emission of highly charged ions clearly show that the ion charge dominates the defect formation at the surface.

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Section: Slow Highly Charged Ionsmentioning

confidence: 95%

Highly charged ion induced nanostructures at surfaces by strong electronic excitations

Wilhelm¹,

El-Said²,

Heller³

et al. 2015

Progress in Surface Science

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“…Strong electron-phonon coupling can then induce local surface modifications in various solids. Recently, HCI-induced surface modifications such as hillocks, [13][14][15] craters, 16 pits, 17 and calderalike structures 18 with nanometer dimensions have been demonstrated. 10 The study of nanostructure formation on surfaces induced by HCI is a relatively new field and still requires a detailed comparison between materials with common and different properties, in order to develop a more general understanding of the underlying mechanisms.…”

mentioning

confidence: 99%

Pyramidal pits created by single highly charged ions inBaF2single crystals

et al. 2010

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In various insulators, the impact of individual slow highly charged ions ͑eV-keV͒ creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved BaF 2 ͑111͒ surface by irradiation with 4.5ϫ q keV highly charged xenon ions from a roomtemperature electron-beam ion trap. Up to charge states q = 36, no surface topographic changes on the BaF 2 surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as can be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence ͑typically 10 8 ions/ cm 2 ͒. The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in BaF 2 .Swift heavy ions ͑MeV-GeV kinetic energy͒ have become an important tool for structural modifications of various materials at the microscale and nanoscale for a wide range of applications in the last two decades. 1-4 One major limitation of using these high-energy ions is the damage creation in deep layers which in some applications should be avoided. The desire to confine the damage to the first few layers, which is essential for applications such as ion projection lithography, has stimulated the interest for the use of slow ͑eV-keV͒ highly charged ions ͑HCIs͒. 5 This type of ions is now readily available after recent developments in ion source technology leading to powerful ion sources such as the electron-beam ion trap ͑EBIT͒. 6,7 While electronic energy loss of swift heavy ions is the major cause of material modifications, 8,9 potential-energy deposition is dominating surface modifications by HCI. 10 During interaction with the solid surface HCI deposit their potential energy ͑the total ionization energy required for producing the high charge state from its neutral ground state͒ within a few femtosecond in a nanometer-sized volume close to the surface. 10-12 Initially the potential energy is deposited in the electronic subsystem of the target leading to strong electronic excitations. Strong electron-phonon coupling can then induce local surface modifications in various solids. Recently, HCI-induced surface modifications such as hillocks, 13-15 craters, 16 pits, 17 and calderalike structures 18 with nanometer dimensions have been demonstrated. 10 The study of nanostructure formation on surfaces induced by HCI is a relatively new field and still requires a detailed comparison between materials with common and different properties, in order to develop a more general understanding of the underlying mechanisms. For this aim and motivated by our recent findings regarding surface nanostructuring of CaF 2 by means of HCI ͑Refs. 13 and 14͒, we selected BaF 2 as one of the ionic alkaline-earth fluorides ͑along with CaF 2 and SrF 2 ͒ which have a wide range of potential applications in microelectronic ...

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“…The electronic excitations in target surface, spread their energy within 100 fs by diffusion into a hemispherical volume around the impact site with a radius large compared to R c [33]. With the projectile charge state increasing, the hemispherical volume, which is proportional to R c 3 as well as proportional to q 1.5 , increases correspondingly.…”

Section: Resultsmentioning

confidence: 99%