Auger line shape measurements using positron annihilation induced Auger electron spectroscopy

Weiss, A. H.; Yang, Sejung; Zhou, Hanhan; Jung, Eun-Sung; Wheeler, S.

doi:10.1016/0368-2048(94)02316-6

Cited by 15 publications

(17 citation statements)

References 18 publications

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“…Even after 26 h (solid triangles upside down), the Auger electrons are clearly detectable, although it was expected that there should be at least one atomic layer of adsorbates on the sample surface. In addition PAES is predominantly sensitive to the topmost atomic layer [4], and hence the copper signal should have vanished.…”

Section: Study Of the Contamination Of A Copper Foil At 150 8cmentioning

confidence: 99%

“…As the positron current is roughly 0.4 pA the measurement time for one spectrum with sufficient statistics was chosen on the order of 10-12 h [6]. Although this measurement time is rather short compared to PAES-experiments that are based on a lab-beam and need measurement times up to several days [4,9], it is still long compared to conventional EAES where a spectrum can be obtained after a few minutes.…”

Section: Reduction Of the Measurement Time And Enhancement Of The Sigmentioning

confidence: 99%

“…Secondly there is no radiation damage due to the positron beam since the implantation site and the place where the Auger process occurs are not identical. Furthermore, PAES examines only the topmost atomic layer since the positron is preferentially trapped in a surface state before it annihilates with an electron [4].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of the surface contamination of copper with the improved positron annihilation-induced Auger electron spectrometer at NEPOMUC

Mayer

Hugenschmidt

Schreckenbach

2008

Applied Surface Science

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Section: Study Of the Contamination Of A Copper Foil At 150 8cmentioning

confidence: 99%

Section: Reduction Of the Measurement Time And Enhancement Of The Sigmentioning

confidence: 99%

See 1 more Smart Citation

Study of the surface contamination of copper with the improved positron annihilation-induced Auger electron spectrometer at NEPOMUC

Mayer

Hugenschmidt

Schreckenbach

2008

Applied Surface Science

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“…Moreover, PAES is much more surface sensitive than AES, since most of the implanted positrons are trapped at the surface bound states and annihilate with electrons in the topmost atomic layer [2,3].…”

mentioning

confidence: 99%

A novel time‐of‐flight spectrometer for PAES

Legl

Hugenschmidt

2007

Phys. Status Solidi (c)

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Positron annihilation induced Auger electron spectroscopy (PAES) uses the annihilation of a positron with an electron of the inner shell of atoms whereas X-rays or high-energy electrons initiate the ionisation in conventional AES. Advantages of PAES are the extremely high surface sensitivity and the higher signal to noise ratio. In order to benefit from PAES one has to use a low-energy positron beam of high intensity, which is available at NEPOMUC at the new Munich research reactor FRM-II. The energy of the Auger electrons is mostly analysed by hemispherical energy analysers. Due to their small solid angle (typically ≥0.1%) and the necessity to scan over certain energy ranges in ≥1eV steps one still needs several hours using an intense positron source like NEPOMUC (at the FRM-II) or even weeks at the lab-beam based on a beta-emitter to obtain an Auger spectrum. For this reason, a novel time-of-flight spectrometer (TOF-PAES) was developed, which efficiently collects the Auger electrons emitted in a solid angle of 2π around the sample, and hence reduces the measurement time to less than one hour. . Positron annihilation induced Auger-electron spectroscopy (PAES) has several advantages over conventional Auger-electron spectroscopy (AES), in which the sample is irradiated with X-rays or keV-electrons to initiate the Auger-process by photo-or impact ionization (XAES or EAES) of core electrons.Due to the low energy of the implanted positrons (several 10 eV), no collision-induced secondary electron background is produced in the higher energy range of released Auger-electrons, whereas commonly measured Auger-spectra show a high background of secondary electrons released by the incoming X-rays or keV-electrons [1]. Moreover, PAES is much more surface sensitive than AES, since most of the implanted positrons are trapped at the surface bound states and annihilate with electrons in the topmost atomic layer [2,3].The main drawback of PAES is the low intensity of low-energy positrons. Another challenge is improving the electron detection in order to compensate for the lack of positron intensity. Augerspectrometers usaually use hemispherical or cylindrical energy analysers. The limited solid angle (few percent) and the energy scans of the analyzers lead to a long duration of measurement for an Augerspectrum: Therefore we developed a novel design for a time-of-flight apparatus for PAES (TOF-PAES) investigations at the positron beam facility at NEPOMUC. With this new Time-of-Flight spectrometer we expect a reduction of the measurement time for an Auger spectrum from hours to less than one hour.

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“…Compared to the traditional high energy electron-induced AES, PAES offers several advantages: (1) surface sensitivity is enhanced because positrons are trapped in an image potential on the surface prior to annihilation; (2) beam-induced damage is minimized because very low energy (~15 eV) positrons are used; and (3) background of secondary electrons is drastically reduced because the energy of the positrons is too low to excite secondary electrons. Recent applications of PAES include distinguishing the different crystallographic planes in semiconductors [68], determining Auger lineshapes [69], detecting surface impurities [70], and studying the growth dynamics of thin films [71].…”

Section: Semiconductor Industrymentioning

confidence: 99%

Auger Electron Spectroscopy

Gunawardane

Arumainayagam

Handbook of Applied Solid State Spectroscopy

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Auger line shape measurements using positron annihilation induced Auger electron spectroscopy

Cited by 15 publications

References 18 publications

Study of the surface contamination of copper with the improved positron annihilation-induced Auger electron spectrometer at NEPOMUC

Study of the surface contamination of copper with the improved positron annihilation-induced Auger electron spectrometer at NEPOMUC

A novel time‐of‐flight spectrometer for PAES

Auger Electron Spectroscopy

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