The chemical environment of Er in H-doped samples was determined by means of extended X-ray absorption fine-structure measurements. Only one family of Er sites was found; coordinated on average with two to three O atoms (as compared with 6 in Er2O3). A new model was developed for the incorporation of Er into H-doped material. According to this model, Er was incorporated in the form of [ErOδ]+3-δ complexes, where δ was less than 3. The minimum configuration energy was found for δ = 3, when the valence requirements of Er were satisfied. The complexes were low-symmetry environments which permitted the Er3+ luminescent transition at 1.54μm.

Environment of Erbium in a-Si:H and a-SiOx:H. C.Piamonteze, A.C.Iñiguez, L.R.Tessler, M.C.M.Alves, H.Tolentino: Physical Review Letters, 1998, 81[21], 4652-5