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 Ec-Eₜ=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×{}10¹² s^-1)exp[(-0.29 eV)/kBT] and at {~}210 K under reverse bias with {ν}=(1.3×{}10⁸ s^-1)exp[(-0.44 eV)/kBT]. 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.