Erbium luminescence from hydrogenated amorphous silicon-erbium prepared by cosputtering

Abstract

Hydrogenated amorphous silicon with small amounts of erbium (Er/Si concentration ∼5 at. %) was prepared by radio frequency sputtering from a Si target partially covered by tiny metallic Er chunks. Four sets of samples were studied: nonintentionally contaminated hydrogenated and nonhydrogenated amorphous silicon-erbium (a-SiEr:H and a-SiEr); nitrogen doped a-SiEr(N):H and oxygen contaminated a-SiEr(O):H. Samples from the first two sets present only faint 1.54 μm photoluminescence characteristic from Er3+ ions even at 77 K. Samples from the other sets show this luminescence at 77 K as deposited, without any further annealing step. Thermal annealing up to 500 °C increases the photoluminescence intensity, and room temperature emissions become strong enough to be easily detected. These results indicate that in an amorphous silicon environment the chemical neighborhood of the Er3+ ions is crucial for efficient 1.54 μm emission. Raman scattering from both as-deposited and annealed samples showed that network disorder relaxation by annealing is not determinant for efficient Er3+ luminescence.