Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

• Published in: Applied physics letters Vol. 88; no. 26; pp. 263119 - 263119-3
• Main Authors: Chao, Y., Houlton, A., Horrocks, B. R., Hunt, M. R. C., Poolton, N. R. J., Yang, J., Šiller, L.
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 26-06-2006
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2216911

The origin and stability of luminescence are critical issues for Si nanocrystals which are intended for use as biological probes. The optical luminescence of alkyl-monolayer-passivated silicon nanocrystals was studied under excitation with vacuum ultraviolet photons
(
5.1
-
23
eV
)
. Blue and orange emission bands were observed simultaneously, but the blue band only appeared at low temperatures
(
<
175
K
)
and with high excitation energies
(
>
8.7
eV
)
. At
8
K
, the peak wavelengths of the emission bands were
430
±
2
nm
(blue) and
600
±
2
nm
(orange). The orange and blue emissions originate from unoxidized and oxidized Si atoms, respectively.