Time-Of-Flight ERDA for Depth Profiling of Light Elements

Abstract

The time-of-flight elastic recoil detection analysis (TOF-ERDA) method is one of the ion beam analysis methods that is capable of analyzing light elements in a sample with excellent depth resolution. In this method, simultaneous measurements of recoil ion energy and time of flight are performed, and ion mass is evaluated. The energy of recoil ions is calculated from TOF, which gives better energy resolution than conventional Silicon semiconductor detectors (SSDs). TOF-ERDA is expected to be particularly applicable for the analysis of light elements in thin films. In this review, the principle of TOF-ERDA measurement and details of the measurement equipment along with the performance of the instrumentation, including depth resolution and measurement sensitivity, are described. Examples of TOF-ERDA analysis are presented with a focus on the results obtained from the measurement system developed by the author.

Sputtering and structural modifications induced in silicon dioxide (SiO2) thin films under (10–40 MeV) Auq+heavy ion irradiation

“…Then, upon irradiation with normal incident Au‐beam, the atomic stoichiometry (O/Si) was also determined for two ion fluence values of ~2.1 × 10 14 cm −2 and ~3.5 × 10 14 cm −2 and found to be reduced to (1.60 ± 0.01) and (1.55 ± 0.01), respectively. The observed slight difference between RBS and ERDA stoichiometry‐values can be presumably due to beam‐induced composition change during ERDA measurements 30,31 (i.e., for a run time of 3 min corresponding to ϕ‐value of 1.9 × 10 13 cm −2 ) and to multiple scattering inside the sample. Also, the concentration of the recoiled C atoms from the carbon foils of ToF detectors 29–31 (~20 μg/cm 2 in thickness) estimated here to be of 0.28% can also affects the determined (O/Si) stoichiometry (see Figures 1 and 3).…”

“…The observed slight difference between RBS and ERDA stoichiometry‐values can be presumably due to beam‐induced composition change during ERDA measurements 30,31 (i.e., for a run time of 3 min corresponding to ϕ‐value of 1.9 × 10 13 cm −2 ) and to multiple scattering inside the sample. Also, the concentration of the recoiled C atoms from the carbon foils of ToF detectors 29–31 (~20 μg/cm 2 in thickness) estimated here to be of 0.28% can also affects the determined (O/Si) stoichiometry (see Figures 1 and 3). Besides, another factor probably affecting the accuracy of the thickness and stoichiometry determination using heavy ion beams is due to the fact that the used SRIM‐stopping powers of He + light ions are more precisely determined than those of heavy ions in compound targets 28,32,33 …”

“…Then, the stoichiometry change versus ion fluence was checked using the ToF-ERDA technique with using 40 MeV Au 9+ heavy ion beam. We plotted thus, in Figure 3 position change during ERDA measurements 30,31 (i.e., for a run time of 3 min corresponding to ϕ-value of 1.9 Â 10 13 cm À2 ) and to multiple scattering inside the sample. Also, the concentration of the recoiled C atoms from the carbon foils of ToF detectors [29][30][31] ($20 μg/cm 2 in thickness) estimated here to be of 0.28% can also affects the determined (O/Si) stoichiometry (see Figures 1 and 3).…”

Revealing the Role of Electrolyte Salt Decomposition in the Structural Breakdown of LiNi0.5Mn1.5O4

“…ToF-E ERDA allows determining the in-depth composition of the LNMO sample by measuring the time of flight and energy of the recoiled atoms. It is a robust method to determine the depth profiles of light elements such as Li, H, and medium-heavy elements . By using an iodine beam ( 127 Iodine 7+ ), the mass of the incident beam is high enough so that the heavy elements present in the stack (Ni, Mn, and Pt) can also be measured.…”

“…It is a robust method to determine the depth profiles of light elements such as Li, H, and medium-heavy elements. 69 By using an iodine beam ( 127 Iodine 7+ ), the mass of the incident beam is high enough so that the heavy elements present in the stack (Ni, Mn, and Pt) can also be measured. The LNMO electrodes were prepared using a 10 nm Pt layer (instead of the standard 70 nm from Figure S9) to minimize the amount of heavy Pt in the stack and increase the sensitivity of ToF-ERDA toward lighter elements such as Li.…”