Helium desorption from cavities induced by high energy 3He and 4He implantation in silicon

A detailed study has been made of helium release from silicon wafers implanted with MeV helium ions at fluences of 5 x 10(16) cm(-2) and 10(17) cm(-2). Thermal desorption spectrometry (TDS), neutron depth profiling (NDP), non-Rutherford elastic backscattering (NREBS) and nuclear reaction analysis (NRA) have been employed to measure the helium content and release rate during isothermal annealing at annealing temperatures of 800 and 1000 degrees C. TDS has also been used for isochronal annealing. Transmission electron microscopy (TEM) is used to monitor changes in morphology in the formed bubble layer. The helium release results can be modeled rather well when it is assumed that the helium initially is present in overpressurized bubbles. The present study reveals a single activation energy for helium release of 1.83 (0.05) eV. (C) 2000 Elsevier Science S.A. All rights reserved.