Unravelling the secrets of Cs controlled secondary ion formation: Evidence of the dominance of site specific surface chemistry, alloying and ionic bonding

Wittmaack, K.

doi:10.1016/j.surfrep.2012.11.001

Cited by 48 publications

(20 citation statements)

References 432 publications

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“…Cs high reactivity ensures a negative ion signal enhancement, along with free radicals scavenging [18]. This source already proved its efficiency on both inorganics [19][20][21][22] and organics [23][24][25]. In this paper, we analyze model systems made of different metals (gold or chromium) and tyrosine multilayer systems deposited on silicon substrates.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

Noël

Houssiau

2016

J. Am. Soc. Mass Spectrom.

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Abstract. The structures developed in organic electronics, such as organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) devices always involve hybrid interfaces, joining metal or oxide layers with organic layers. No satisfactory method to probe these hybrid interfaces physical chemistry currently exists. One promising way to analyze such interfaces is to use in situ ion beam etching, but this requires ion beams able to depth profile both inorganic and organic layers. Mono-or diatomic ion beams commonly used to depth profile inorganic materials usually perform badly on organics, while cluster ion beams perform excellently on organics but yield poor results when organics and inorganics are mixed. Conversely, low energy Cs + beams (<500 eV) allow organic and inorganic materials depth profiling with comparable erosion rates. This paper shows a successful depth profiling of a model hybrid system made of metallic (Au, Cr) and organic (tyrosine) layers, sputtered with 500 eV Cs + ions. Tyrosine layers capped with metallic overlayers are depth profiled easily, with high intensities for the characteristic molecular ions and other specific fragments. Metallic Au or Cr atoms are recoiled into the organic layer where they cause some damage near the hybrid interface as well as changes in the erosion rate. However, these recoil implanted metallic atoms do not appear to severely degrade the depth profile overall quality. This first successful hybrid depth profiling report opens new possibilities for the study of OLEDs, organic solar cells, or other hybrid devices.

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Section: Introductionmentioning

confidence: 99%

Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

Noël

Houssiau

2016

J. Am. Soc. Mass Spectrom.

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“…Salt addition can, under some conditions, improve ionization through adduct formation [13]. Similarly, Cs flooding or Cs + bombardment enhances ionization through [M + Cs] + formation [14, 15]. Several groups have employed the strategy of using H 2 O as a source of protons, particularly since it is the natural matrix of biological materials.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Reactive Ionization with Cluster Secondary Ion Mass Spectrometry

Tian

Wucher

Winograd

2015

J. Am. Soc. Mass Spectrom.

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Gas cluster ion beams (GCIB) have been tuned to enhance secondary ion yields by doping small gas molecules such as CH4, CO2, and O2 into an Ar cluster projectile, Arn+ (n = 1000–10,000) to form a mixed cluster. The ‘tailored beam’ has the potential to expand the application of secondary ion mass spectrometry for two- and three-dimensional molecular specific imaging. Here, we examine the possibility of further enhancing the ionization by doping HCl into the Ar cluster. Water deposited on the target surface facilitates the dissociation of HCl. This concerted effect, occurring only at the impact site of the cluster, arises since the HCl is chemically induced to ionize to H+ and Cl−, allowing improved protonation of neutral molecular species. This hypothesis is confirmed by depth profiling through a trehalose thin film exposed to D2O vapor, resulting in ~20-fold increase in protonated molecules. The results show that it is possible to dynamically maintain optimum ionization conditions during depth profiling by proper adjustment of the water vapor pressure. Protonation and H–D exchange in the trehalose molecule M was monitored upon deposition of D2O on the target surface, leading to the observation of [Mn* + H]+ or [Mn* + D]+ ions, where n = 1–8 hydrogen atoms in the trehalose molecule M have been replaced by deuterium. In general, we discuss the role of surface chemistry and dynamic reactive ionization of organic molecules in increasing the secondary ion yield.

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“…For instance, according to ref. [29], removal rate of silicon substrates produced by Cs ions at 2 keV, normal incidence, is expected to be below one atom per incident ion. On the other hand, at larger current yield, cesium ions sputtering properties are well known, making this element widely used for negative ion sources based on surface bombardment [30].…”

Section: Figmentioning

confidence: 99%

Ion microscopy based on laser-cooled cesium atoms

Viteau¹,

Reveillard²,

Kime³

et al. 2016

Ultramicroscopy

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We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a lasercooled cesium beam adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130 pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5 keV range are obtained with a resolution around 40 nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of 1 eV, offering great prospects for lithography, imaging and surface analysis.

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Unravelling the secrets of Cs controlled secondary ion formation: Evidence of the dominance of site specific surface chemistry, alloying and ionic bonding

Cited by 48 publications

References 432 publications

Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

Dynamic Reactive Ionization with Cluster Secondary Ion Mass Spectrometry

Ion microscopy based on laser-cooled cesium atoms

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