Elastic Recoil Detection Analysis and Time of Flight ERDA


Elastic Recoil Detection Analysis (ERDA) is a non-destructive nuclear analytical method. ERDA is a technique for depth profiling of light elements in thin layers and in multilayer systems. Measurement with this method may be performed on amorphous as well as crystalline materials. ERDA uses high energy (~1MeV/amu) heavy-ion beams to kinematically recoil and depth profile low atomic number target atoms. The heavy ion projectile only needs to have a greater mass than the target atom. Alpha particles are commonly used to obtain recoil spectrum for hydrogen and its isotopes.

Features of ERDA:

  • good sensitivity for light elements

  • wors mass resolution

  • good depth resolution (average 10 nm)

Parameters of RBS:

  • ions: He+ and heavy ions

  • energy of ions: order of MeV for He+ and order of 10 MeV for heavy ions

  • detection limit: 1mg/g

  • depth range: order 100 nm

Time of flight ERDA

The mass-depth ambiguity can complicate the interpretation of ERDA spectra. This ambiguity results because the energy of the recoiled ions depends on the mass and depth of the target atom in the sample. Here is a benefit of Time of flight - ERDA (TOF-ERDA), the recoil ion energy and mass we can measured independently. TOF-ERDA measured simultaneous the velocity and energy of the recoiled atoms from the target. The velocity of recoil atoms is determined by measuring the time required to pass between two thin foils at TOF1 ad TOF2 with a corresponding TOF distance. As the atoms passes through the foil, secondary electrons are ejected and accelerated into detector to mark a timing event.

Ions for TOF-ERDA ranging from O to Au at tens of MeV.