Diffusion of hydrogen implanted in alpha-quartz during air annealing

alpha-quartz samples were implanted with 20 keV H-2(+)-ions to fluences of 5 x 10(16) H/cm(2) at a target temperature of 77 K. Rutherford Backscattering in channeling geometry (RBS-C) revealed that an amorphous surface layer of 1.54 x 10(18) atoms/cm(2) forms under these conditions. Resonant nuclear reaction analysis (RNRA) utilizing the H-1(N-15, alpha gamma)-resonance at 6.385 MeV beam energy was used to measure the implanted hydrogen profile, The samples were then annealed in air for 1 h at temperatures between 300 degrees C and 950 degrees C. After annealing, RBS-C and RNRA were again employed to study the alterations of the hydrogen profile and the amorphous layer induced by the heat treatment. In contrast to the observation with alkali ions no epitaxial regrowth could be detected even after the 950 degrees C annealing. Below about 450 degrees C also no changes of the hydrogen profile were observed, while at about 600 degrees C almost all hydrogen has left the sample. This behavior fits nicely to the results obtained for other alkali implantations, Hydrogen as the lightest (and smallest) group-I atom becomes mobile at the lowest temperature and also the observed trend that the quality of the regrown layer decreases with decreasing atomic number of the implanted species has been confirmed, since no epitaxial recrystallization has taken place. (C) 2000 Elsevier Science B.V. All rights reserved.