Hydrogen cobalt complexes in p-type silicon

We report on three cobalt-hydrogen related deep levels H(50): E-v + 0.09 eV, H(90): E-V + 0.17 eV and H(150): E-V + 0.22 eV. The levels are formed by wet chemical etching or remote hydrogen plasma treatment and successive annealing at 400 K in cobalt-doped float-zone p-type silicon. The level H(150) is bistable and exhibits a fully reversible transition between an electrically active and an electrically neutral configuration after zero-bias or reverse-bias annealing at temperatures between 310 K and 400 K. We tentatively assign H(90) and H(150) to a CoH complex and H(50) to a CoH2 complex.