Calibration of the Harwell series II Bi-implanted RBS standards

Abstract The Bi content of several Series II Rutherford backscattering (RBS) standards (Bi-implanted silicon) has been calibrated by comparison with an earlier Series I standard and also by an independent measurement of the absolute RBS yield. Both methods agree within ± 1% on a given sample. Independent measurements at each of CRNL and CBNM Geel indicate Bi implant uniformity better than 1% across each target and good agreement (± 1%) in the absolute Bi content of exchanged samples. Most of the Bi assays agree within the combined counting statistics (± 1%) with Geel's previous Series II calibration value of (4.75 ± 0.07) × 10 15 cm −2 ; however,two targets were found to contain ∼ 4% more Bi. Harwell's implantation records show that the two higher dose samples were both cut from the same implanted wafer and that poor vacuum conditions during implantation may have been responsible for this excess dose. Since the implantation history of each wafer has been well documented, there should be no difficulty in establishing which calibration value is appropriate for an individual standard.