Search

The erbium-doped hydrogenated amorphous silicon suboxide films containing amorphous silicon clusters were prepared. The samples exhibited photoluminescence peaks at around 750 nm and 1.54 μm, which could be assigned to the electron-hole recombination in amorphous silicon clusters and the intra-4f transition in Er[sup 3+], respectively. Correlations between the intensities of these two photoluminescence peaks and oxidation and dehydrogenation of the films during annealing were studied. It was found that the oxidation is triggered by dehydrogenation of the films even at low annealing temperatures, which decisively changes the intensities of the two photoluminescence peaks. On the other hand, the increase of Er content in the erbium-doped hydrogenated amorphous silicon suboxide film will enhance Er[sup 3+] emission at 1.54 μm, while quench amorphous silicon cluster emission at 750 nm, such a competitive relationship, was also observed in the erbium-doped silicon nanocrystals embedded in SiO[sub 2] matrix. Moreover, we found that Er[sup 3+] emission is not sensitive to whether silicon clusters are crystalline or amorphous. The amorphous silicon clusters can be as sensitizer on Er[sup 3+] emission as that of silicon nanocrystals. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Silicon nanocrystals (Si-NCs) with different sizes embedded in SiO2 matrix were synthesized by phase separation and thermal crystallization of SiOx/SiO2 supperlattice approach. The optical constants and band gap expansion of Si-NCs have been investigated by spectroscopic ellipsometry, based on the Maxwell–Garnett effective medium approximation and the Forouhi–Bloomer optical dispersion model. Similar spectra shapes but smaller values of Si-NCs optical constants with respect to bulk crystalline Si is observed. With the size of Si-NCs decreasing from 6nm to 2nm, the band gap increases from 1.64eV to 2.56eV. The band gap expansion, as compared to bulk crystalline Si, which agrees with the prediction of first-principles calculations based on quantum confinement effect, is presented in this paper. [Copyright &y& Elsevier]

Abstract: Erbium-doped hydrogenated amorphous silicon suboxide films containing silicon clusters (a-SiO x :H) were prepared. The samples exhibited photoluminescence (PL) peaks at around 750nm and 1.54μm, which could be assigned to the electron–hole recombination in silicon clusters and the intra-4f transition in Er3+, respectively. We compared annealing behaviors of Si clusters and Er3+ emission and found that Si clusters emission depends strongly upon crystallinity of Si clusters, whereas Er3+ emission is not sensitive to whether it is Si nanocrystals (nc-Si) or amorphous Si (a-Si) clusters. The erbium-doped a-SiO x :H films containing either a-Si clusters or nc-Si have the same kind of Er3+-emitting centers. Based on these results, it is concluded that a-Si clusters can play the same role on Er3+ excitation as nc-Si. [Copyright &y& Elsevier]