Hydrogen induced detrapping of transition metals in amorphous silicon

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Abstract
The implantation of H into amorphous Si is shown to passivate the structural defects that act as traps for fast diffusing transition metal impurities such as Cu or Pd. The depth distributions of Cu or Pd, as determined by Rutherford backscattering spectrometry, are governed by the H distribution for concentrations up to 5 at. % and temperatures between 250 and 500 °C. The H can cause complete detrapping of the metal impurities leaving a Gaussian deficit in their equilibrium distributions mirroring the H depth distribution. The H is thus more strongly bonded to the traps than Cu or Pd. The total trap concentration is estimated to be 2.2±0.9 at. % for 350 °C annealing. Implanted F also induces detrapping of Cu and Pd. These detrapping phenomena demonstrate equivalence between the structural traps that control diffusive properties and the defects that control electrical and optical properties.