ERBIUM LUMINESCENCE FROM HYDROGENATED AMORPHOUS SILICON-ERBIUM PREPARED BY COSPUTTERING

Hydrogenated amorphous silicon with small amounts of erbium (Er/Si con centration similar to 5 at.%) was prepared by radio frequency sputteri ng from a Si target partially covered by tiny metallic Er chunks. Four sets of samples were studied: nonintentionally contaminated hydrogena ted and nonhydrogenated amorphous silicon-erbium (a-SiEr:H and a-SiEr) ; nitrogen doped a-SiEr(N):H and oxygen contaminated a-SiEr(O):H. Samp les from the first two sets present only faint 1.54 mu m photoluminesc ence characteristic from Er3+ ions even at 77 K. Samples from the othe r sets show this luminescence at 77 K as deposited, without any furthe r annealing step. Thermal annealing up to 500 degrees C increases the photoluminescence intensity, and room temperature emissions become str ong enough to be easily detected. These results indicate that in an am orphous silicon environment the chemical neighborhood of the Er3+ ions is crucial for efficient 1.54 mu m emission. Raman scattering from bo th as-deposited and annealed samples showed that network disorder rela xation by annealing is not determinant for efficient Er3+ luminescence . (C) 1997 American Institute of Physics.