DEVELOPMENT OF A COMPACT HIGH-RESOLUTION RBS SYSTEM

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We have developed a compact high-resolution RBS system including a small accelerator and a high-resolution magnetic spectrometer. The energy resolution was measured to be 0.33keV for 292keV HeィイD1+ィエD1 ions at an acceptance angle of 0.3msr. Monolayer resolution was demonstrated with this system.Because the acceptance angle is rather wide, a so-called "kinematic broadening" reduces the apparent energy resolution especially for light elements. We designed an electrostatic quadrupole lens (Q-lens) for correction of the kinematic broadening. Using the Q-lens, depth profiles of nitrogen atoms in a ultrathin films of silicon oxynitride could be measured with depth resolution of atomic level. Initial oxidation process of Si(001) surfaces was also investigated with the HRBS system. It was found that the oxidation proceeds in the layer-by-layer mode and that the first atomic layer is not completely oxidized at room temperature. The initial stage of Ge/Si(001) epitaxial growth was also studied by HRBS. The intermixing of Ge and Si was observed at growth temperature of 500℃ even in the sub-monolayer coverage region.It was demonstrated that high-resolution elastic recoil can be performed using the developed HRBS system. A depth resolution of 0.28nm was obtained in a depth profile of hydrogen in silicon crystals.A more compact high-resolution RBS system was developed in collaboration with Kobe Steel Ltd. The dimensions of the full system, including an accelerator, are 3.8m(L)×2.8(W)×2.35m(H). This system, called HRBS-500, is now commercially available.