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Published in G B Stringfellow, Gallium Arsenide and Related Compounds 1991, 2020
G. E. Höfler, J. N. Baillargeon, J. L. Klatt, K. C. Hsieh, R. S. Averback, K. Y. Cheng
Standard ion beam analysis techniques were employed for the channeling study.4 A beam of 1.3 MeV deuterium with a current of ≈ 150 nA was obtained from a Van der Graaff accelerator. The final spot size was set by a 3mm aperture placed at the entrance of the sample chamber. The current incident on the sample during the measurement was monitored by measuring the yield of ions backscattered from a rotating gold wire which intercepted the beam. Although radiation damage to the specimen was unlikely under these irradiation conditions, transmission electron microscopy (TEM) analysis was performed on the sample; no evidence of structural damage in the epilayer was observed. Figure 1 shows the backscattering spectra obtained from a MOCVD grown sample with a hole concentration of 4 × 1019 cm−3 when the ion beam was aligned with <100> surface normal. A minimum yield of 0.026 was determined by comparing the height of the aligned and random signals obtained from the GaAs substrate. A second spectra along the <110> direction was also obtained. Since backscattering techniques are based on statistical events, the experimental uncertainty is minimized by increasing the total number of events. For this reason, the backscattered intensity was integrated over the 1μm thick carbon-doped layer. The ratio of counts in the channeling to random directions, or “normalized yield,” unambiguously showed that at least 27% (± 8%) of the C was located in interstitial sites.
Towards Quantifying the Composition of Expanded Austenite
Published in Tom Bell, Katsuya Akamatsu, Stainless Steel 2000, 2020
M.P. Fewell, P. Garlick, J.M. Priest, P.T. Burke, N. Dytlewski, K.E. Prince, K.T. Short, R.G. Elliman, H. Timmers, T.D.M. Weijers, B. Gong
Heavy-ion elastic-recoil detection analysis (HI-ERDA) is an ion-beam analysis technique for the compositional depth-profiling of materials. In this technique, incident ions penetrate into a sample, interacting with atoms and much less frequently with nuclei in the sample. Some recoil ions from nuclear scattering are ejected through the sample surface, permitting their detection. Typically, a wide range of species with a wide range of energies is ejected, so that particle identification is required. This is achieved either by time-of-flight measurements or by measurements of energy loss in a gas-ionisation detector. The numerous interactions of both the incident and the recoil ions with electrons in the sample cause loss of kinetic energy. Consequently, the energy with which the recoil ions emerge from the surface is a function of the depth of the nuclear collision, with lower-energy recoils originating from deeper inside the sample. By measuring the energy spectra of the recoil ions, stoichiometric information can be correlated with depth.
Charged-Particle (Activation) Analysis
Published in Zeev B. Alfassi, Max Peisach, Elemental Analysis by Particle Accelerators, 2020
J. P. Friedel Sellschop, Harold J. Annegarn
An important aspect of ion beam analysis is indeed that of instrumentation. The modem accelerator, be it single-ended DC, tandem configuration, or compact cyclotron, is increasingly user-friendly and reliable in its performance. To an equal extent, the detector and related electronics aspect has advanced: energy dispersive detectors, the semiconductor surface barrier detector for charged particle analysis, and the lithium-drifted or intrinsic germanium and silicon detectors for gamma-ray and X-ray spectrometry at high resolution, together with the advent of powerful but simple-to-use (often computer-based) multichannel pulse height analyzers, have contributed to the transition from awkward experimental device(s) to application-without-hassle devices.
Determination of the Oxygen Concentration in GDP Thin Films Using Rutherford Backscattering Spectroscopy
Published in Fusion Science and Technology, 2021
Xiaojun Ma, Qi Wang, Zongwei Wang, Xiangyu Wan
The first consideration whether RBS is suitable for characterizing the GDP sample is to calculate the behavior of incident ions into the target sample, such as the penetration depth of ions with specific energy and the irradiation damage of the target sample. It is noted that the irradiation damage, which is an inherent issue in all ion beam analysis techniques, must be taken into account. In order to verify the penetration depth and damage effect of incident ions on GDP samples, the interaction between incident ions and target samples is simulated by the SRIM-2013 software. In this simulation, the GDP film is composed of carbon 43 at. %, hydrogen 55 at. %, and oxygen 2 at. %. The incident ion with an energy of 2 MeV and an incident angle of zero degrees is defined as a point source on the surface of the GDP film with a thickness of 10 μm and a density of 1.15 g/cm3.