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 E(c) - E(t) = 0.16 eV is observed by deep-level transient spectroscopy. The center anneals at approximately 100 K under zero bias with a decay constant v = (3.0 X 10(12) s-1)exp[(-0.29 eV)/k(B)T] and at approximately 210 K under reverse bias with v = (1.3 X 10(8) s-1)exp[(-0.44 eV)/k(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.