The electron paramagnetic resonance spectrum of float-zone material, after implantation with protons, contained a strongly temperature-dependent signal that arose from a vacancy-type defect. The signal exhibited monoclinic-I symmetry below 65K, and trigonal symmetry above 100K. This symmetry change, together with a hyperfine splitting from a single proton, permitted the unambiguous identification of the defect as being VH0; the neutral charge state of a vacancy which contained a single H atom. A striking similarity between the properties of VH0 and VP0 (the E center) corroborated the identification.

B.B.Nielsen, P.Johannesen, P.Stallinga, K.B.Nielsen, J.R.Byberg: Physical Review Letters, 1997, 79[8], 1507-10