Elastic recoil detection

Elastic Recoil Detection Analysis (ERDA), also referred to as forward recoil scattering (or, contextually, spectrometry), is an Ion Beam Analysis technique in materials science to obtain elemental concentration depth profiles in thin films. This technique is known by several different names. These names are listed below. In the technique of ERDA, an energetic ion beam is directed at a sample to be characterized and (as in Rutherford backscattering) there is an elastic nuclear interaction between the ions of beam and the atoms of the target sample. Such interactions are commonly of Coulomb nature. Depending on the kinetics of the ions, cross section area, and the loss of energy of the ions in the matter, Elastic Recoil Detection Analysis helps determine the quantification of the elemental analysis. It also provides information about the depth profile of the sample.The incident energetic ions can have a wide range of energy from 2 MeV to 200 MeV. The energy of the beam depends on the sample to be studied. The energy of the beam should be enough to kick out (“recoil”) the atoms of the sample. Thus, ERD usually employs appropriate source and detectors to detect recoiled atoms.However, such experimental setup is expensive and along with a source requirement of high energy ions appears to make this technique relatively less commonly used for materials characterization. Moreover, the angle of incidence that an ion beam makes with the sample must also be taken into account for correct analysis of the sample. This is because, depending on this angle, the recoiled atoms will be collected. Although it is not very clear, the assumption for why this technique is not very well known would be due to the fact that it is hard to have a perfect combination of the source, the angle of incidence, and the detector to have the best characterization of the sample. Such problem would make the technique very time consuming and tedious.This article provides information about ERDA that has been around for a long time, since the mid-1970s, still not very well known. The article provides detailed information about the High ion Incident ERDA. However, Low ion Incident ERDA is still not neglected. The comparative analysis of overall ERDA with other techniques such as TEM, AFM, XRR, NR, VASE, XPS, and DSIMS is also mentioned. The article briefly touches upon the history of ERDA but the main focus is on the technique itself. Comprehensive information on the instrumentation as well as its applications in elemental characterization and depth profile are provided.ERDA and RBS have similar theory but minor differences in the set-up of the experiment. In case of RBS, the detector is placed in the back of the sample whereas in ERDA, the detector is placed in the front. This difference in the set-up is shown in figure 1 on the right.