- 1. Lattice Defects in Semiconductors 23, 1-22 (1975) , Institute of Physics, London , “EPR Studies of the Lattice Vacancy and Low-Temperature Damage Processes in Silocon”, G. D. Watkins.EPR studies of silicon irradiated at 20.4 K and 4.2 K by 1.5 MeV and 46 MeV electrons are described. In 46 MeV irradiations the dominant defects formed appear to be divavancies and other multiple defect aggregates which liberate vacancies throughout the anneal to room temperature as they reorder, recombine, etc. For 1.5 MeV irradiations group III atoms play a vital role in p- and n-type materials in trapping interstitials and stabilizing damage. Carbon and oxygen are not effective interstitial traps at these temperatures. Evidence of limited vacancy migration during irradiation is also cited. Two distinct excited configurations of vacancy-oxygen pairs are identified as precursors to A-centre formation in n-type silicon. The kinetics for their conversion to A-centres depends strongly upon the Fermi level as does the isolated vacancy migration energy whhich is measured to be 0.18 Â± 0.02 eV for the Vï¼ charge state. The vacancy has four charge states, Vï¼‹, V0, Vï¼ and Vï¼. Kinetics for hole release from Vï¼‹ reveals an activation barrier of 0.057 eV. The concentration of Vï¼‹ at 20.4 K in boron-doped material indicates the corresponding donor level even closer to the band edge, approximately EV ï¼‹ 0.039 eV. Jahn-Teller energies for V0, Vï¼‹, and Vï¼ are estimated from stress-alignment studies and confirmed to be large. Kinetics studies for reorientation from one Jahn-Teller distortion to another are also described for each charge state.
Updated at 2010-07-20 16:50:39