Secondary ion emission from various metals and the semiconductors Si and GaAs induced by mega-electronvolt ion impact

Matthäus, R.; Moshammer, R.; Hayn, G. von; Wien, K.; Della‐Negra, S.; Beyec, Y. Le

doi:10.1016/0168-1176(93)80069-q

Cited by 10 publications

(3 citation statements)

References 16 publications

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“…The error in secondary ion yields is typically ,10%. Spectra were dominated by Ga 1 ions and small amounts of As 1 [19]. Positive secondary ion yields increase as a function of q, but the increase is much weaker than for total yields.…”

Section: J C Banks and B L Doylementioning

confidence: 89%

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

et al. 1998

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We have measured total ablation rates and secondary ion yields from undoped GaAs(100) interacting with slow ͑y 6.6 3 10 5 m͞s͒, very highly charged ions. Ablation rates increase strongly as a function of projectile charge. Some 1400 target atoms are removed when a single Th 701 ion deposits a potential energy of 152.6 keV within a few femtoseconds into a nanometer-sized target volume. We discuss models for ablation of semiconductors by intense, ultrafast electronic excitation.[S0031-9007(98)07165-8] PACS numbers: 79.20.Rf, 34.50.Fa The interaction of slow ͑y , 2 3 10 6 m͞s͒ highly charged ions (SHCI) with surfaces is an active field of research [1,2] with applications in materials analysis [3] and modification [4][5][6][7]. In slow ion-solid collisions, where the projectile velocity is smaller than the Bohr velocity ͑y Bohr 2.19 3 10 6 m͞s͒, most target electrons move faster than the projectile and readily react to the perturbation during a collision. SHCI, such as Xe 441 and U 901 , are extracted from electron beam ion traps (EBIT) [1] while fast ͑y ¿ y Bohr ͒ highly charged ions are formed by charge state equilibration in gaseous or solid targets using heavy ion accelerators. Charge states of SHCI are far in excess of mean equilibrium charge states formed by slow ions when traveling through solids. The latter are ϳ11 at the velocities selected in this study [8]. Consequently, SHCI neutralize and deexcite rapidly when they interact with solid surfaces. Charge state equilibration times are in the order of a few femtoseconds [8]. The potential energy of SHCI, i.e., the sum of the binding energies of electrons removed to form the ion, is deposited during deexcitation. Individual SHCI deposit tens to hundreds of keV of potential energy into a small (nanometer scale) target volume at the surface. Insulators and thin ͑ϳ10 nm͒ semimetallic conductors react to this intense, ultrafast, and localized electronic excitation by emission of large numbers of neutral particles [5,9] and secondary ions [3,9]. For bulk semiconductors, no increase of ablation rates as a function of projectile charge was observed for Si interacting with Ar q1 , q # 91 [10]. Reports for GaAs are controversial. Using Ar q1 , q # 91, Varga et al. [5] found no increase of the sputtering yield with charge. The null result was interpreted in the context of a model of defect-mediated potential sputtering. For the same projectiles, Mochji et al. [7] observed a charge dependent sputter yield increase, and the results were interpreted using a Coulomb explosion model [11]. The ionization probability for secondary ions was not determined in either of these two studies. In this Letter we report on measurements of charge state dependencies of total sputtering and secondary ion yields from GaAs interacting with slow, very highly charged ions up to Th 701 . Using projectiles in much higher charge states than were used in earlier studies [5,7,10], we find results that do not follow predictions of established defect mediated or Coulomb explosion models of electro...

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Section: J C Banks and B L Doylementioning

confidence: 89%

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

et al. 1998

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“…Recently, the imaging concept of the reaction-microscope has been extended to the detection of electrons emitted from surfaces (Hattass et al (2003), patented by Moshammer and Ullrich (1998)). For ions emerging from solids, this technique has been developed early by Moshammer et al (1990) (Matthäus et al 1991(Matthäus et al , 1993 and was recently used by Schmidt-Böcking et al (2003) (see also Jalowy et al (2002Jalowy et al ( , 2002aJalowy et al ( , b, 2003Jalowy et al ( , 2003a).…”

Section: New Developmentsmentioning

confidence: 99%

“…In order to boost the resolution for high-energy electron imaging ( eV 100 > ) Weber et al (2003) (Matthäus et al (1991(Matthäus et al ( , 1993) and was recently used by Schmidt-Böcking et al 2003(see also Jalowy et al (20022002a,b;). …”

Section: New Developmentsmentioning

confidence: 99%

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

et al. 2003

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Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to π Microccopes -the "bubble chambers of atomic physics" -mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields.The present review concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of highintensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using Reaction Microccopes. Third, for electron and ion-impact, the investigation of twoelectron reactions has matured to a state such that first fully differential cross sections (FDCS) are reported. Forth, comprehensive sets of FDCS for single ionisation of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is shortly envisaged.2

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Secondary ion emission from frozen argon by ²⁵²Cf fission fragments

Wien

Spieth

1995

Rapid Comm Mass Spectrometry

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In order to study sputtering of Van-der-Waals solids by MeV ion impact, films of solid argon condensed onto a metallic substrate at a temperature of 10 K were irradiated by "*Cf fission fragments. The secondary ions emitted from the surface were investigated by a time-of-flight technique. The mass spectra are dominated by a cluster series Ar: with n ranging from 1 to about 30. Comparatively high absolute ion yields were determined; the yield of Ar' was 48 ionshmpact. The mass line of Ar + was broadened due to ejection energies of up to 50 eV. The line shape of the cluster ions indicates delayed particle emission. Some of the observed phenomena are not typical for electronic sputtering at MeV energies; they are briefly discussed. These are the first and preliminary results of a systematic exploration of high energy sputtering from solid rare gases.Electronic sputtering of frozen argon has been frequently studied and is one of the best-understood sputtering phenomena (see, for instance, the review article of Johnson and Schou).' In solid argon, swift heavy ions generate, by electronic excitation, mobile excitons, which get self-trapped near the surface and cause sputtering by their decay-either directly or via the formation and subsequent de-excitation of excimers. These processes have been explored mainly by energy distributions of neutral argon atoms combined with luminescence spectroscopy.Little is known about the mechanisms forming ionized sputtered particles. The mean ionization energy of Ar (20.1 eV) is orders of magnitude higher than the cohesive energy (0.08 eV). Therefore, Ar' is produced by relatively highly energetic processes-in accordance with the finding that the ejection energy of argon ions is distinctly higher than that of the neutral atoms. ' The highest electronic sputtering yields (85 Ar atoms per impact) have been observed with 4He beams at an energy loss of 1.3 M e V / m g /~m * .~The aim of the present work was to extend the investigation of sputtering from solid Ar in the high energy loss regime, where additional sputter processes should occur, such as gas flow sputtering"' or ablation due to shock wave propagation. The *' *Cf fission fragments used to irradiate the frozen Ar layers have an energy loss of 36 MeV/mg/cm' (light group of fragments) and 38 MeV/mg/cm' (heavy group). In the following, we present our very first results on ion emission from frozen Ar. (We have also planned systematic experiments with frozen Ne, Kr and Xe including studies of neutral particles.) EXPERIMENTALThe time-of-flight (TOF) mass spectra of Ar ions were measured by means of a plasma desorption mass spectrometry (PDMS) technique developed recently for studies of organic frozen gasesx The liquid-nitrogen trap of this machine has now been replaced by a liquidhelium cryostat, which provides a temperature of 10 K at the sample substrate. The part of the instrument, which holds the cold target, the 12 pC "I' Cf source and the acceleration grid, is sketched in Fig. 1. During the TOF measurements, a steady stream of...

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Secondary ion emission from various metals and the semiconductors Si and GaAs induced by mega-electronvolt ion impact

Cited by 10 publications

References 16 publications

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

Secondary ion emission from frozen argon by ²⁵²Cf fission fragments

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Secondary ion emission from various metals and the semiconductors Si and GaAs induced by mega-electronvolt ion impact

Cited by 10 publications

References 16 publications

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

Secondary ion emission from frozen argon by 252Cf fission fragments

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Secondary ion emission from frozen argon by ²⁵²Cf fission fragments