Thin film analysis using heavy ions: Correction of the mismatch between calculated and observed detection yields in ToF-ERD measurements, new type of energy detector and advanced analysis software for the community.


Main funder

Funder's project number: 330283


Funds granted by main funder (€)

  • 438 874,00


Funding program

  • Research post as Academy Research Fellow, AoF (Academy of Finland)


Project timetable

Project start date: 01/09/2020

Project end date: 31/08/2025


Summary

The single most important characterization need of the thin film research and industry has been the quantitative depth information of elements within the films. In the past, one very competitive method was Rutherford Backscattering Spectrometry (RBS). Today there is an increasing demand to analyze all the elements in ultrathin films, down to sub monolayer concentrations and a great limitation of the RBS is the poor ability to detect light elements. To overcome the limitations in RBS, Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) can be used as an alternative, and all sample elements can be quantified down to hydrogen. However, when low energy heavy ions, like the ones from the most common accelerators, are used to measure heavy elements, in the scattering event the two bare nuclei are considerably shadowed by the electrons. This screening effect leads to significantly reduced scattering probability and, unfortunately, no existing model can describe this well enough. A second major limitation of ToF-ERDA is the hindered performance of the energy detector to reach higher count rates than 1000 counts/s. The small count rate yields to long measurements and the poorer collected statistics reduces the sensitivity of the technique.
This project will consist of three main work packages. The WP1 will focus on the systematic measurement of heavy ion scattering cross-sections for a wide range of ion-target atom combinations, scattering angles and incident ion energies. The goal of WP1 is to gain deep understanding of the heavy ion screening including the limitations of present models, and to generate a new model which more accurately reproduces the measurements. The WP2 will focus on the development of new high-performance energy detector for ERDA which will enable at least 4-7 times faster measurements than today. These two WPs have the highest scientific discovery potential. In the smallest WP3 the Jyväskylä developed Potku-analysis software will be fully updated to autofit the Monte Carlo simulations of ERDA and RBS measurements, and in later stages, to use the new screening model.
These three main WPs will fuse together as substantially more quantitative and faster thin film analysis. The results will be disseminated by open access data and articles, free of charge detector drawings, hands-on workshop for PhD students and post docs to build detector components and with Gnu Public License Potku analysis software.


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Last updated on 2020-04-11 at 10:26