Abstract:
Hydrogenated and unhydrogenated Si-nanocrystal/Si
dioxide (Si-nc/SiO2) composites were obtained from SiyO1−y
(y = 0.36, 0.42) thin films deposited by plasma-enhanced chem-
ical vapor deposition. The unhydrogenated composites were fab-
ricated by promoting the Si precipitation through the thermal an-
nealing of the films in the flowing pure Ar at temperatures up to
1100 ◦C. The hydrogenated composites were obtained from identi-
cal films by replacing the Ar with (Ar + 5% H2) in the annealing
step. The photoluminescence (PL) of the composites was studied
as a function of the annealing temperature (T ), annealing time,
and pump laser power. The PL intensity increases with increasing
annealing temperature and time; however, it increases faster and
attains several hundreds percent larger values when the anneal-
ing is performed under (Ar + 5% H2) as compared to the an-
nealing under pure Ar. Fourier-transform infrared spectra show
that H in these hydrogenated samples incorporates mainly as Si–
H bonds. The dependence of the PL spectra on y, T , and laser
power are consistent with the assumption that light emission in
both the hydrogenated and unhydrogenated Si-nc/SiO2 compos-
ites originates from the bandgap transitions involving the electron
quantum confinement in the Si-ncs. The PL spectra from the hy-
drogenated films are skewed to the red as compared to those from
the unhydrogenated ones. The bulk of the data indicates that H
passivates the nonradiative recombination centers, most probably
Si dangling bonds in disordered Si-nc/SiO2 regions, thus increas-
ing the number of Si-ncs that contribute to the PL and modifying
the distribution of the emission wavelengths.
Index Terms—Nanotechnology,photoluminescence (PL),plasma
chemical–vapor deposition (CVD), semiconductor films, silicon.
