INTERFERENCE-FRINGES IN SYNCHROTRON SECTION TOPOGRAPHY OF IMPLANTED SILICON WITH A VERY LARGE ION RANGE

Silicon crystals implanted with 9 MeV protons to the dose of 5x10(17) cm(-2) were studied with X-ray topographic methods using both conventi onal and synchrotron radiation sources. After the implantation the cry stals were thermally and electron annealed. The implantation produced large 600 mu m thick shot-through layer while the total thickness of t he samples was 1.6 mm. It was confirmed by means of double crystal top ography that the whole crystal was elastically bent. The transmission section patterns revealed both parts of the implanted crystal separate d by strong contrasts coming from the most damaged layer and distinct interference fringes which appeared on one side of the topograph only. The location of the fringes changed when the beam entered the other s ide of the sample. The mechanism of fringe formation was studied with numerical integration of the Takagi-Taupin equations, especially study ing the intensity distribution in the diffraction plane. The simulatio ns reproduced the location of the fringes in different geometries and indicate that they can be caused both by variable crystal curvature an d variable ion dose.