Microscopic nature of the Er3+ emission in mixed amorphous-nanocrystallineSi : H films

ErO6 complexes, where every Er3+ ion is surrounded by six oxygen atoms form ing an octahedron with C-3v point symmetry, are found to best describe the strong Stark splitting of the characteristic Er3+ emission in the 1460-1610 nm range. An a-Si:H matrix serves as an ideal semiconductor host to permit codoped O atoms to form an optimal octahedral ligand field around the Er3 ions. The observation of sharp intense Stark peaks for temperatures betwee n 153 and 300 degreesC and of strong enhancement of the Er3+ emission after 350 degreesC annealing can be understood first by diffusion and then outdi ffusion of weakly bound hydrogen atoms in the a-Si matrix. (C) 2001 America n Institute of Physics.