Deep state of hydrogen in crystalline silicon: Evidence for metastability

After proton implantation into n-type silicon at 45 K, a bistable hydrogen center with a band-gap level ${\mathit{E}}_{\mathit{c}}$-${\mathit{E}}_{\mathit{t}}$=0.16 eV is observed by deep-level transient spectroscopy. The center anneals at ∼100 K under zero bias with a decay constant ν=(3.0×${10}^{12}$ ${\mathrm{s}}^{\mathrm{-}1}$)exp[(-0.29 eV)/${\mathit{k}}_{\mathit{B}}$T] and at ∼210 K under reverse bias with ν=(1.3×${10}^8$ ${\mathrm{s}}^{\mathrm{-}1}$)exp[(-0.44 eV)/${\mathit{k}}_{\mathit{B}}$T]. In both cases the center regenerates by forward-bias injection at low temperatures. The decay without (with) reverse bias reflects capture of one (two) electron(s). The metastability is ascribed to hydrogen jumps between bond-center and tetrahedral sites as a result of changes in charge states.