Some applications of high-resolution RBS and ERD using a magnetic spectrometer

Abstract

We have developed a high-resolution Rutherford backscattering spectroscopy (RBS) system with a 90°C sector magnetic spectrometer ( δE E ∼ 0.1% , including the energy spread of the incident beam). Energy spectra of sub-MeV He 1 ions backscattered from single crystal surfaces are measured with the high-resolution RBS system. The RBS spectra observed at grazing exit angles (several degrees) consist of several well-defined peaks which correspond to the ions scattered from successive atomic layers indicating the achievement of monolayer resolution. Examples of the application of this novel technique are presented. The spectrometer is also used for elastic recoil detection (ERD) measurements. By installing an electrostatic deflector between the magnet and the ion detector, recoiled ions are distinguished from the scattered ions. This method has a considerable advantage over the conventional ERD concerning the depth resolution and also has an advantage over the recently developed high-resolution ERD, which combines an electrostatic or magnetic spectrometer with a time of flight (TOF) technique, regarding the measurement time. A depth resolution of about 0.8 nm is achieved in the measurement of the hydrogen distribution in silicon crystals.