Metastable defect states in hydrogen-implanted silicon

We report the first observation of the concentration reversible changes of defects produced by hydrogen implantation in silicon. EPR and IR-absorption measurements were used. It was found that after implantation and annealing of a sample at approx. 450 deg C the concentration of shallow donors and the intensity of the IR-absorption bands (3.36 μm, 3.40 μm and 3.47 μm) change reversibly upon annealing at temperatures lower than 300 deg C. The temperature dependence of the equilibrium concentration of the shallow donors between 100 deg C and 300 deg C as well as the transients following changes in temperature have been determined. The activation energies for relaxation of a donor to a neutral state and for transition to an electrically active state are 1.23 eV and 1.74 eV, respectively. We conclude that the phenomenon is due to interaction of hydrogen atoms and intrinsic defects produced in silicon by hydrogen ion implantation. (author)